Hey guys,

I've done pretty much everything I can think of, but my car still runs lean at anything above 4-5 psi. Once it leans out, it seems very slow on boost so I know something is wrong. I've searched and searched on this subject, but can't seem to pinpoint what it is. Here is what I have done:

-New Fuel Filter
-Took off FMU and put on a friend's, but still leans out
-Thought it could have been FCD's, but have tried 2 different kinds and still leans out
-New O2 sensor

I just can't seem to figure out what it can be. I guess it could possibly be the fuel pump, but I don't know if that is a logical choice or not.

Please help me, I don't want to keep spending money on stuff that isn't the culprit.

EDIT:
Guess I should let you know what I have. I have a Walbro 255 and Vortech FMU on stock injectors only running 6 psi tops, but I have lowered the wastegate down to 3 and it stays rich on that boost level. Anything above 4-5 though and it leans out and is very sluggish feeling.

Mike D
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OK, I just got done swapping fuel pumps with my friend's Walbro and it still does the same thing. So bad fuel pump is out. I have run out of ideas so if anyone has one, post up.

Mike D
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what are you using to log?

fmu, im not familiar with, is this like a rrfpr? if so what rate?

I knew the FCD wasnt the problem.

His FMU im guessing is probably a 12:1 and he is using a worthless nb02 a/f gauge.

You cannot trust those gauges, seriously. but if your sluggish then you have something f'd up, are you sure the FMU is hooked up right and you have the correct calibration kit in it?

My opinion first off would be to ditch the FMU and get a SFMU.

I even have an SFMU for sale for cheap in the F/S section.

-MIKE-

Stroked 2.2L

I don't have any money to spend on more parts right now, I'm in debt to pay off what I have already. At WOT, those gauges *should* read in the rich part of it and it doesn't so that right there is a red flag for me. I read when I was searching that the ECU may pull timing when the A/F ratio gets too lean and that's what I may be feeling when I try to boost.

Yes, my FMU is hooked up right. It's by the fuel tank with the side port going to the FPR and the bottom port going to the tank. I've checked it all over and searched to see if it was right and it was.

For what I have and what I am doing, my parts should be ok. Yes, an SFMU would be safer to have, but I'm not looking for double digit boost levels right now. I'm just looking for a quicker daily driver. 6 psi or so should be ok for an FMU to handle.

Mike D
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How old is your fuel filter?

Just replaced it a couple nights ago and didn't help the problem. I searched and came up with that as a possible culprit so I replaced it and nothing

Mike D
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Is the fuel pressure even rising? FP Gauge?????

I eat emo kids for breakfast

1995 Eagle Talon (SOLD)
72' SuperBeetle
72' Standard Beetle
56' Deluxe Beetle

I don't have one of those to tell if it is or not. Can you rent those at an auto store or do you have to buy it?

Mike D
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-MIKE-

Stroked 2.2L

-----------------------------
95 Eclipse RS-T
Custom T3 60 Trim turbo kit.



-Josh

-MIKE-

Stroked 2.2L

Actually, you had it wired up wrong on the inside and used a different colored wire than you said you normally do. If you did test it out, you would have caught that easily. It wasn't my fault that it was wired incorrectly on the inside to make wiring it up on the outside wrong.

I have a boost gauge, oil psi gauge, water temp, a/f. MAP sensor checks out ok. I've tested the voltage on that numerous times. We have a datalogger here, but are having a hard time getting it to work on my car. No CELS.

Mike D
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-----------------------------
95 Eclipse RS-T
Custom T3 60 Trim turbo kit.



-Josh

well im not here to bicker...

what does your MAP drop to while under boost?

-MIKE-

Stroked 2.2L

Stays at like 4.61v at WOT. Did some pulls the other day in it and thats what it was around. Hooked up a multimeter to the leads and drove around checking.

Mike D
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Originally posted by DJ420a

Originally posted by DSMcrazy3

Originally posted by eclipse982nrRST

Smell that? ::sniff sniff:: Smells kinda like bullshit..

Um, who in the fuck are you? Ive seen youve posted twice in this thread without an ounce of help. All your doing is knocking. Only real bullshit I see is what your typing. The way I see it, if he was wrong he was wrong, but he's still trying to help. Sit back and shut the hell up unless your gonna help.

-MIKE-

Stroked 2.2L

Originally posted by DJ420a

Originally posted by DSMcrazy3

Originally posted by eclipse982nrRST

Smell that? ::sniff sniff:: Smells kinda like bullshit..

Um, who in the fuck are you? Ive seen youve posted twice in this thread without an ounce of help. All your doing is knocking. Only real bullshit I see is what your typing. The way I see it, if he was wrong he was wrong, but he's still trying to help. Sit back and shut the hell up unless your gonna help.

-----------------------------
95 Eclipse RS-T
Custom T3 60 Trim turbo kit.



-Josh

He's the one who posted this for help, not you. Are you the mouse in his pocket? Do you sit on his shoulder? Im 99% sure your not his mommy.

He's a big boy now, he doesnt need a tag team partner, so my comment stays and you are still posting in this thread with nothing to remedy the problem. I hope your roommate/partner/whatever gets this figured out....done

Im not going to play post tag with you, I gave my 2 cents.....done.

You two shut up before I lock this.

As for your problem it's kinda hard to know if your FMU is working properly without a FP gauge. No way to know it's rising. I kinda have a feeling your problem is centered around there but I don't think it's with the FMU itself. I know you said it's installed right but humor me.

List out exactly how it's installed. Where each line goes from the FMU and which side of the FPR and which port on the fuel pump bracket? A picture would be even better.

Also, one other thing. Check for any place the vac line to the FMU or the fuel return line can be pinched. That'll cause you some problems too.

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

stupid question, but you do have a missing link right?

and did you rewire your fuel pump with 10 gauge? because that's generally something to do. just get on ebay and buy a dsm fuel pump rewire kit. the stock wiring can't handle the higher loads upgraded fuel pumps need. could be the problem. and this statement is from my own research and also the experience of a friend. difference for him was night and day, same car.

95 Eclipse RS - Sold and In Montana Now
Project 95 GSX - In Full swing.

Mabye a clogged injector? Don't know?

when i first boosted my rs i had a shitload of problems. what it was in the end was my injectors had been jamming and nobody was able to diagnose the problem. when your car falls on its face, is it leaning out instantly and falling hard or is it a slow leanout?

got that megasquirt!

I have a FCD.

Well right now if I put it in 5th gear and punch it going about 55 or so, it starts to build boost and stays in the rich. Right when it gets to 2 psi it starts to make it's way to stoich and then at about 3 psi it goes to lean.

I was told to measure my disk in my FMU. When I got it, they said it was a 12:1 fmu, but it has a seating ring with the disk and I was read that a 12:1 isn't suppose to have a seating ring in it. It's a Vortech FMU.

Side port is going to the stock FPR and the bottom port (opposite of vacuum source) is going to the return of the fuel tank. I might retry my friends 12:1 fmu again and make sure the vacuum line isn't pinching on anything.

Mike D
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Are you feeling like a complete loss of power when you say its going lean?

-MIKE-

Stroked 2.2L

At times yes. Sometimes I can't tell a difference, but a lot of the times it feels like I am pulling and then just stops pulling, but still goes forward, ya know? Hard to explain.

Mike D
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Have you tried completely removing the FCD and Missing Link and boosting just on the MAP sensor itself yet? What happens then?

-MIKE-

Stroked 2.2L

Same thing. Eventually hits fuel cut if it's in boost for like 5 or more sectonds. It will get to around 3 psi and then cut all the way into lean pretty much.

I'm replacing my valve cover gasket right now, oil change, and afterwards I'm gonna pull out the disk of my fmu and measure it to make sure I have a 12:1 and not some other ratio.

Mike D
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OK, I'm guessing this could be my problem?

Mike D
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how many inches should it be?

-MIKE-

Stroked 2.2L

Yeah, the 12:1 disc is literally the entire size of the inside chamber in the FMU with no ring. Must be a 10:1 disc setup. I had my car go crazy lean when I was having a gasket leak on my old FMU. Once you take them apart so many times they get harder and harder to seal up perfectly. Make certain you have absolutely NO vacuum leaks from the intake manifold to the FMU too.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

when you put your car back together, tap a gauge into the fuel rail and run it long enough for a passenger to hold it outside and see what preesures your getting while under boost.at 3psi, you should be at about 75-80psi fuel press. (on stock injectors) i have 4 red top 30#ers, collecting dust.those whith an sfmu and your shit should be boosting as smooth as mine.up to 10-11psi.

got that megasquirt!

I think it's suppose to be 2.72" or something. WAAAAAAY off. I need another now Anyone have one for cheap??

Mike D
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Hey total, I seen one on Houstonimports.com while browsing for turbo parts lol.

http://www.houston-imports.com/forums/showthread.php?t=331124&highlight=vortech

-Jim EX-DSM Owner....

I got in contact with another guy on H-I and will be picking up a Vortech 12:1 tomorrow for $45. He said I could open it up and make sure it was a 12:1 before I buy it. If that doesn't go through (for some reason?) I'll check in on this one, thanks a lot.

Mike D
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Why don't you just spend the $25 and buy the right disc from Vortech?

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

Because I wanted to have it running before this sunday for the H-Town DSM Galveston Cruise. You should come along Dino.

UPDATE:
I installed the 12:1 FMU and adjusted my FCD a little bit and now the gauge reads I lean out at around 5 psi. It doesn't feel like I lean out though, no noticable loss in power. Should I not worry about it anymore? I set my wastegate at around 6-7 psi and it seems to pull the whole time.

Mike D
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Risking a lean condition on our engine's is a big no no. Do you have an EGT gauge? I used to notice lean conditions a lot easier with my EGT than I do with my old narrowband A/F gauge (get a wideband 02 sensor like the one from zeitronix). I originally tested my fuel pressure with a fuel pressure gauge screwed into the test port on the fuel rail(can rent them for free from Autozone and other similar stores). Just prop the gauges under the passenger windshield wiper so you can read it while driving and take a roll of electrical tape (or somthing similar in thickness) and lay it flat near the hose on the wiper sill. That way when you shut the hood it doesn't pinch the hose. 5-7 psi should be roughly in the 85-90 psi range I believe.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

You CANNOT rely on a NARROWBAND O2 A/F gauge!

I dont care what anyone says, they are not accurate, I think they are only accurate in a stoicho-metric state. Just my .02

Get the correct gauges now before you keep risking it though,

Get yourself a EGT and atleast a FP gauge.

-MIKE-

Stroked 2.2L

I eat emo kids for breakfast

1995 Eagle Talon (SOLD)
72' SuperBeetle
72' Standard Beetle
56' Deluxe Beetle

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

Mike D
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______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

Walbro has 2 versions of the 255lph pump. One is the standard pump and one is the high pressure pump, model # GSS342 which is the one needed for people running stock injectors with the 12:1 FMU. This pump can do up to roughly 140psi and I have run it with stock injectors and a 12:1 FMU for 6 months now which runs roughly at 105psi at 8-9psi....easily. If yours didnt run high enough, it probably wasn't the high pressure model. Either that or something was faulty in the setup somewhere.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

I have the HP model actually. I pulled it out and found the number on it.

Mike D
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did it fix the problem?

-MIKE-

Stroked 2.2L

The easiest way to check and see if the fuel pump is on its way out and no longer can build up enough high pressure (yes the Walbro's tend to do this occasionally) is simply to screw in the fuel pressure tester into the fuel rail and take a pair of pliers and pinch the ruturn line for a second. The dial should instantly go beyond 100 psi for that moment. If it hovers somewhere around 80-90psi, its on its way out. Oddly, it still is usable for people running 60psi setups with no problems. Strange. I believe someone once said that it's the regulator valve? in the pump that prematurely weakens and cant handle the high pressures.....dont quote me on that though.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

Do you know where exactly I can get a fuel pressure gauge tester? I have tried the Autozone here and they don't carry it to buy or rent. I would only be looking for like a $30 one like what was stated.

I am thinking of re-wiring my fuel pump and if that doesn't help, buy an Accel inline fuel pump from a member on here.

Mike D
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just google online for a fuel pressure tester. They go from about $30-$60

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

Does anybody think the fuel pump rewire mod will help my leaning problem a little bit? I did some searching, but couldn't really come up with a definitive answer as if it helped out a lot or no.

Mike D
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-MIKE-

Stroked 2.2L

Yeah I put the new one in and it still wants to run lean anything more than 3 psi. I even opened this one up before I installed it and it does have a significantly bigger disk in it. Nothing bigger can possibly go in so I'm assuming that it is a 12:1. I put 2 springs on my internal wastegate to make it open at 3 psi and I can floor it and it will stay rich. Just if I use my MBC to turn it up any, my A/F gauge goes into the lean area again.

Mike D
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-MIKE-

Stroked 2.2L

Well I already asked if I should just not worry about it and then. So is it something to worry about or no?

Mike D
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-MIKE-

Stroked 2.2L

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

Scenario:

Narrowband 02 v.s. Wideband o2

Now lets rate your Girlfriend.

I'd say she's a 9 on the narrowband scale (1 - 10)

Now on the wideband scale - She's 6' tall, black hair, smoking long legs, tight little ass, she likes Prada & Burberry and she fucks like a wild woman.
She also Like bacon and eggs for breakfast Every morning before her Hour long jog.
at 7am.
Before that she's naked.



See the difference

Much more precise.

I eat emo kids for breakfast

1995 Eagle Talon (SOLD)
72' SuperBeetle
72' Standard Beetle
56' Deluxe Beetle

Originally posted by Blizare
Scenario: Narrowband 02 v.s. Wideband o2 Now lets rate your Girlfriend. I'd say she's a 9 on the narrowband scale (1 - 10) Now on the wideband scale - She's 6' tall, black hair, smoking long legs, tight little ass, she likes Prada & Burberry and she fucks like a wild woman. She also Like bacon and eggs for breakfast Every morning before her Hour long jog. at 7am. Before that she's naked. See the difference Much more precise.

-MIKE-

Stroked 2.2L

Well in my case, without that gauge, I would have probably blown up my engine by now. The fact that it doesn't read rich anymore at all under anything more than 4 psi flagged my attention and made me begin to look into it.

I just got a fuel pressure gauge and hooked it up and at idle it reads about 55-60 psi. Under boost, like 6-7 psi it stays at about 70-75 psi. Which is not good I believe.

Mike D
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with the car idling, take a pair of pliers and pinch the return line coming off the FMU(restricting all fuel from returning to the tank and forcing the fuel pump to reach its highest possible PSI. The Walbro 255LPH-HP maxes out at 120psi (I looked it up for you) so if the pump itself is working fine, it should peg the needle on the pressure tester (assuming it goes to 100psi). If not, you either have a serious blockage between the fuel rail and the tank....or your Walbro is crapping out. I've had 2 Walbro Gss342's go bad on me in my past with the same issue you're having so its possible. I believe its the check valve inside the pump assembly which causes this, not the pump itself. My guess is it will max out at 90psi.

Do that and report back.

P.S. your static fuel pressure on your setup should be 60psi (car idling with the vacuum hose going to the FPR disconnected and plugged). at idle, with the vacuum hose connected to the FPR, it should be between 49-55psi (the FMU inline can sometimes cause some restrictions so it varies between these points depending on the setup). At 6-7 PSI you should be closer to 90-95psi.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

So is the check valve replacable or do you have to buy a whole new pump? I'll go and try doing that pinch thing now.

Mike D
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Alright, just did that and the gauge only read around 70 psi. So what does that mean I have to do now? Buy a new fuel pump? Or can I just get another inline pump on that line?

Mike D
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I believe its the actually the relief valve inside the pump assembly which causes this not the check valve that I stated before. When it see's pressure exceed a certain amount (in this model its supposed to be set for 120psi I assume)it bleeds off pressure back into the tank. Neither which I believe are servicable as far as I am aware of. Yeah, sounds like a bad pump. Ideally, the best place to check this is if there was a test port on the fuel line coming directly out of the tank (I am currently making one that goes inline between the fuel pump assembly and the feed line back on top of the tank). Since we cant check it there, our only educated guess can be that its either a LARGE restriction between the pump and fuel rail....or the pump. The biggest culprit would be the fuel filter but you said its new so its highly doubtful. A pinched fuel line running back to the tank is always possible too.

I imagine you could try adding an inline pump if you wanted but a replacement pump should do the trick.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

What about a faulty stocker FPR since it is still hooked up with the FMU?

-MIKE-

Stroked 2.2L

It IS possible I suppose but blocking off the return line should overpower anything else regulating pressure and force the pump to reach its maximum potential. It has nowhere to go but as high as the relief valves pressure limit will allow it to go.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

Alright, well I will look into getting a new walbro in the next couple weeks. Hopefully that is the problem because I won't have money to try another possibility. I still need to get a new manifold and new stainless steel return line kit for my car all before December. I will be quitting my job and moving back to MN so I won't have any income coming in for parts for a little while.

Mike D
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Alright guys New Walbro 255 HP fuel pump came in today so I installed it and VOILA! No more leaning. Upped the boost to 6 psi and she stays rich and pulls good. Thanks everyone for your help. Jack_of_trades, points to you because you pinpointed the problem, thanks a million!

Mike D
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No problem man. I'm glad you are back on track, leaning out scares the crap out of me lol. Oh, I just put together a fuel pressure test port setup that can go back at the fuel pump assembly. I'm not quite done with the cosmetics of it (previous owner hacked up the floor and siliconed it like a blind man) but I will have a write-up completed this weekend with step-by-step instructions. I have a 7psi loss from the pump to the fuel rail at idle with the stock fuel filter and lines(50psi at the rail, 57psi at the tank)....not good with a 12:1 FMU. Heres a few pics to give you an idea of whats going on:

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

Wow, yeah make sure to make a writeup for that thing. So thats the pressure at idle you are talking about having a 7 psi difference?

Mike D
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Yeah. Your fuel pump maxes out at around 120psi, at 110 psi, its still usable for the HP #'s you'd be putting out. My guess would be that in my setup, if I was running 105-110psi at the fuel rail (that'd be around 9psi of boost using a 12:1 FMU) I'd be maxing the pump out back at the tank. That means I would be getting barely any volume of fuel up to the rail causing a lean condition even with the pressure being high enough. I used -06 AN fittings on my test port adapter because I will be upgrading to -06 stainless steel braided fuel lines with a high flow fule filter in the near future. That alone should stop my pressure drop.

I recall reading somewhere that the stock fuel filters are only good up to 100psi and can only flow around 2LPM(120LPH)@60PSI so its pretty much maxed out on any FMU setup, causing serious flow restrictions. I plan on using a high pressure(200psi), high flow (1500lb/hr)fuel filter like the aeromotive #12308. There are tons to choose from at jegs.com and summitracing.com

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

WOW.

7 Pages and all you needed was a new walbro.

Wow.

I eat emo kids for breakfast

1995 Eagle Talon (SOLD)
72' SuperBeetle
72' Standard Beetle
56' Deluxe Beetle

Well, now its 8 pages thanks to your addition,lol.

Jamie-
-AUTOMATIC turbo'd 95 Talon ESI@8psi (stock internals)14.0sec=1/4 mile

-2003 Mitsubishi Evo VIII

Yep yep, she's running good now. Just putting on my new manifold, turbo, and external wastegate today.

Mike D
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