Guys, I'm new to the turbo world, and I've got a 370ish HP beast, but it doesn't exactly run perfectly. The guy I bought the car from thinks the problem is a wastegate not fully opening, and I'm thinking it is an A/F ratio problem. Here is what happens.

Diving the car is just fine as long as you don't go over about 40% throttle in any gear. It will climb to 7K just fine, but under WOT at about 3500-4000 RPM this SEVERE hesitation will start happening. The car will jump and sputter all the way to about 5500 RPMs. My friend told me he can tell when the car is doing it from behind too because I huge cloud of smoke comes out. As soon as I get past 5500 RPMs the car will just take off like a rocket.

Additional info: I was watching the SAFC and watching the Kar reading. While driving, if it is not doing its sputtering the Kar will go to about 320 MAX, but when the car is sputtering it will skyrocket to about 1700. After 5500 rpms the Kar stays high but doesn't keep going up so far, it just slowly increaases from 1700 to about 1850 until I let off on the throttle.

Any ideas???

My dad is thinking possibly wastegate, and another friend of mine is thinking it could be an EGR problem, if I have one. Do I have an EGR, and could there be a problem with this?

Thanks guys!


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Moved from Advanced Tech (BECAUSE IT'S NOT ADVANCED!!!) to 1g/4g63 tech

Give us info on every bit of the setup. Turbo, injectors, milage, evreything possible cause the hesitation could be any numbe rof things. Could be a dead TPS sensor, or fuel cut or any number of things depending on factors.

What year car etc. Info please.

List of mods:
Ported and cliped Big 16g
Ported Exhaust Mani and O2 housing
Apex i N1 catback 3"
Injen intake with K&N filter
Centerforce dual friction clutch, lightened RRE flywheel 10k miles on clutch and flywheel
Nippon Denso 550 inj. Super AFC, 255lph fuel pump
Greddy Big FMIC
Greddy Type S blowoff valve
Autometer EGT & Boost guages

1997 GSX 45,500 miles

Sorry guys, I should have included this in the first place.



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need afpr imo..

#1 check for a boost leak

#2 How old are the wires/plugs? I had the EXACT same symptoms (note, possibly not same problem, just symptoms) with a t-25 that just needed new (bigger) wires and plugs

Vandy

Yes start with an AFPR....you need one with a 255 Fuel Pump. Do you have a logger for this thing? Did the previous owner get this thing tuned? How did he come up with the AFC settings? How much boost are you running? Any CELs being thrown? Did you check your plugs wires and such? It sounds like it is Fuel Cut but it could be a number of other things.....

Originally posted by BigBald
Yes start with an AFPR....you need one with a 255 Fuel Pump. Do you have a logger for this thing? Did the previous owner get this thing tuned? How did he come up with the AFC settings? How much boost are you running? Any CELs being thrown? Did you check your plugs wires and such? It sounds like it is Fuel Cut but it could be a number of other things.....

AFPR? Are you guys asking for the settings on the SAFC?

This car has the walbro(?) 255 fuel pump. I don't have a logger for the car, just the SAFC. The previous owner had the engine built up from Road Race Engineering in Colorado Springs. I don't know if this car has always had this problem or not, but I'm going to call him and ask.

The car was running 22psi of boost on 93 octane gas, but I can't find 93 in Wyoming, so I filled up on 91 but I haven't ran full boost on that gas, I'm going to turn the boost down tomorrow just to protect myself from overboosting.

There was a CEL thrown one time when the car was doing its studdering thing, and it stayed on the rest of the day yesterday, and today, but I just noticed it went off on the way home from the office today. ???

The plugs on the car are a colder plug he said. He changed them every 3,000 miles with every oil change. He said the colder plug is better for the car since it is boosting so much. And the wires can't be any older than 15,000 miles, at the absolute max.

The car could definitely be having fuel cut, but that doesn't make sense because it runs just fine from 5,500-redline, why would it just cut out from 3500-5500??

I'll run outside in a bit and get the SAFC settings for everyone to gaze at.



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Here is what I found guys:

High Throttle
1000 -25%
2500 -36%
4000 -36%
4500 -36%
5500 -36%
6000 -36%
6500 -36%
7000 -36%

Lo Throttle
1000 -18%
2500 -27%
4000 -28%
4500 -28%
5500 -28%
6000 -28%
6500 -28%
7000 -28%

TH Point
Lo 15%
Hi 75%

NE Point
NE1 - 1000
NE2 - 2500
NE3 - 4000
NE4 - 4500
NE5 - 5500
NE6 - 6000
NE7 - 6500
NE8 - 7000

Dec. -Air
Thr ****%
NE1 10%
NE2 10%

Sensor Type
Karman

Car Select
Cyl - 4
Thr - Diagonal up and right arrow

That is all I've got guys, if you need anything else please let me know.



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changed the plugs every 3k? Either he's nuts or he's lying to you...i've never heard of people bothering to do that, that seems a bit extreme...

also, APFR is a fuel pressure regulator...can't tell if you were confused or not

and seriously, check for a boost leak before you spend any real money...you should do that periodically anyways, and i've had problems with my Type S..in fact its really starting to piss me off

vandy

P.S. I didn't know there was a road race in CO.... are there others?

it could be the fact youve gone from a 120hp car to a 350hp monster and your feeling the turbo lag, but if its throing a cel and smoke out the back its probably not

sounds like your car is bogging. i doubt its a boost leak because it would happened all the time under wot. also check under the intake pipe and look at the ecu wires to make sure none of them are frayed. (thats what happened to mine)

checking what code the cel is throwing might help you a little bust most likely it will be emission system related.

wastegate problem would be cause by the flapper being partially open or shifted the wrong way. you wouldnt be throwing smoke out of the back for that tho or giving a code.

sorry i didnt anwser the question really but i can only guess what the problem is
(shoulda had him fix the problem before you bought it imo)

I would love to have had him fix it before I bought it, but he and RRE have tried different things to try to fix it and have been unsuccessful. It doesn't seem like it's going to be that big of a problem, just annoying until I can figure it out. And as long as I'm not driving like a bat out of hell, everything is fine. Sure would be nice to experience WOT with this beast though.



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im gonna take a wild guess that your turbo needs to be rebuilt. have you taken off the intake piping and felt inside the turbo? push on the pin in the middle and pull it adn try to wiggle it around. you say your pushing 370hp on a 16g? thats near the top of the scale for that turbo and it might near the end of its life



the wastegate not fully opening would cause the turbo to spike and you to boost like crazy.

it is a big 16G turbo, the guy says it can push 25psi and the car is only pushing 20-22psi. The turbo has only been on the car for less than 2 years and about 15K miles.



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i have seen turbos go with less miles on them for various reasons. just a thought

btw 22psi on 91 gas isnt a good idea either. might wanna turn it down to around 16-18psi. im not positive but a 16g at 25psi probably isnt very efficient. i think theyre only rated for 350hp (maybe that was the s16g?)

you know what this sounds like to me..
it sounds like engine missfire..
Does it still have the stock engine (7bolt) or does it have the 1G engine?

post a pic of the engine bay....

with an 255lph pump you need and AFPR.....your stock on is just no good any more. Start with a AFPR and take your car to autozone to have your CELs read to make sure you don't have any. Just because the light went off doesn't mean the codea are gone.

Yes this is still the stock 4G63, it is not a 1G motor.

I will definitely look into the AFPR, but maybe this is just me, but why would I have problems like fuel cutoff, misfire, or turbo problems from 3500-5500, but then it runs just fine again from 5500 to redline???

Edit: Engine Pic

Originally posted by Vandy420a
changed the plugs every 3k? Either he's nuts or he's lying to you...i've never heard of people bothering to do that, that seems a bit extreme...

Am I extreme? I change plugs every oil change about every 1500-2000 miles...

On topic: Sounds like fuel probs to me... check your fuel pressure when that stuff is going on, and try to see what its doing on a dyno with a wideband..

edit: And check out CEL's, plugs and wires, and other normally checked things like everyone else said.

I would also invest in a logger of some sort for that thing.

http://www.highaltitudeimports.com/archive/index.php/t-4211

It looks like this guy was having similar problems, do you think anything he did would help solve my problem?



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Well, I turned the boost down to 15-16psi at lunch today. Thanks for the reminder CK. I already knew I shouldn't be boosting to 22psi on 91 octane, so I hadn't hit full boost since I gased up on 91. The guy I bought it from always filled up with 93 and ran the 22psi, but I can't find 93, so in the meantime, the boost is down.

The problem is still there too, not as bad, but still there.



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P.S. I didn't know there was a road race in CO.... are there others?

I looked at road race's website and I guess they are in California? The guy I bought the car from used to live in CA, he must have had all the mods done while he was there. ??



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Guys, I have been all over the internet today, hope the boss doesn't find out. RRE suggests these settings on a 2G with all the mods I have except the RRE 3" DP and cat.

My settings are not set to these, should I change them? Could this be a problem?

Also, what does "honeycombs all in" mean?

Thanks

2G Turbo
Big 16 G Turbo, Apex Cat Back, RRE DP-3" Cat, Filter, 19psi, Front Mount I/C, Walbro 255 HP in tank pump, 550cc Injectors, honeycombs all in, Adjusting screw left alone, Big GReddy FMIC

Low Setting:
1K +-2 2K -4 3K -6 4K -10 5K -10 5.5K -10 6K -10 7K -10
High Setting:
1K -21 2K -23 3K -24 4K -23 5K -22 5.5K -22 6K -21 7K -18
TH-Point
Lo 30% Hi 80%



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Well i still think you need an AFPR. If you don't want to get one then shrink your fuel pump down to a 190lph which is dyno proven up to 425whp.

I don't have a problem with getting one, I just want to make sure that is what I need. If it is so highly suggested, I will get one anyway, but I want to know all my options before I spend $250 on an AFPR.



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"honeycombs all in" refers to the MAS, that box behind the K+N filter. If you dont' know if your honecombs are in, take off the filter and look at the MAS...you should literally see honeycomb type things inside...

Vandy

P.S. not to knock anyone with the spark plugs comment, i'd just heard you should change them every 15 THOUSAND, but I'm still on a T-25 so to be honest, you probably know much more than I....i'd just never heard that before...

I would start with the little things first. Pick up some new plugs. (Get the 7's if your running over 20psi)
Make sure they are gapped PROPERLY! That alone will cause the symptoms you're talking about.

I'd recommend checking the cheap and easy things first...IE, spark plugs, wires, boost leaks. The symptoms you're describing sound to me like either not enough spark, or too much fuel, causing you to bog at that certain RPM range.

It is cheap and easy to check/replace plugs and wires and check the gap. I'm sure there's way to meter the MAS as well.

It looks like you're pulling out a lot of fuel with the SAFC, maybe even almost too much. So I would guess it's spark related over fuel, unless that Walbro is overpowering the stock FPR and dumping fuel. Wish you had a datalogger to check.

P.S. - I knew EVERYONE that posted on that thread you copied from High Altitude Imports except for the guy that was having the problem. They are all friends of mine. :)

no if it was missing the Honeycombs it would idle like crap...it would run fine once its on the go (mine was missing them)
do a tune up before youspend the big bucks

As everyone saidyou need to check for leaks ,wires , plug gap ect. But imo i think your having a fuel problem. I think you need to log a run and i am almost 100% sure u will see where your problem is. I mean how did the guy get to those setting on the safc without logging ?







#333

I am no expert on 4g's, but it sounds like you are running pig rich. Throwing black smoke?

My car does the same thing (420A). At low RPM's and partial throttle it would bog and hesitate because it was dumping way too much fuel at once. Once it hit 15psi all was sweet and the car pulled very damn good. Have in mind I was using a 10:1 disk on the FMU. Just my 2 cents.

Thats what i said...the 255 ALMOST always outflows the stock AFPR causing symptoms you described. But it could be the other things that some are mentionaing such as plugs and wires. After you check the "easy" stuff start looking at the fuel system. IF you want to learn more about the AFPR or the 190 fuel pump, you can run a search on DSMTalk or DSMTuners....plenty of info there. Also....please pick up a logger, with the mods you have you will need one...you will thank me later.

I have a 255 walbro with no tuning issues. My old roommate ran a 255 on his T-25, Big 16G, and Green with no AFPR. He had no tuning problems. You do not NEED an AFPR with the 255 as said above. It is not necessary. I am still using the stock FPR and I have zero problems as well.

I don't have time to read this entire thread, but I wanted to make that point.

I did say ALMOST always.....there are special cases out there like you and your friend. Then there are those who slap it on and immediately have problems like the one he is describing.

Here is what i would do if I were you and that was my car. After checking the obvious things and determining that those are not your problems. I would either invest in a logger and log a few runs and see what is going on or take it to the dyno and have it dyno tuned and see what is going on. If you do either of those two methods I can gaurantee you will find out what is going on. Your best bet is a logger cause dyno time can be very expensive. Either way this should help you eleimante the guessing game you want to avoid.

Is there a such thing as a cheap logger? I saw the dsmlink is like $650, and I'm guessing I would be essentially plugging the car into my laptop, right? It sounds like a good investment, but do I need all the things this program has to offer? Will this tell me if the engine is running lean/rich. That is one thing I am surprised isn't on this car. NO A/F RATIO GAUGE! :shrug

Dyno time is pretty much out of the question. I found a dyno shop, I never talked to them, but since I'm in Wyoming, I'm pretty sure they will only have a FWD or RWD dyno setup. AWD is much harder to find.

Guys I appreciate all of your input. I will definitely be checking the gap on the plugs, will probably replace the wires, probably plugs too, and I will probably buy an AFPR pretty soon too.





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DSMlink rocks! It allows you to tune and monitor pretty much everything! Definitely read up on it and you'll see how much it would benefit your setup. You'll also be able to sell the SAFC to recoup some of the cost.

MAC Autosports in Denver has an AWD dyno. It's a great shop run by really cool guys. If you feel like another road trip down here I'm sure myself and some of the knowledgeable guys in my car club could probably help you tune it.

Dsmlink is prabably the best thing next to a standalone.
www.dsmlink.com

There are cheaper ways to tune as well
www.dsmchips.com

I am chipping my ecu this week. Best 90bucks you will ever spend
For both of these methods you will need a eprom ecu which will run you 200-300 bucks. If you had a 95 it would cost you nothing.

If you dont want to go with either of these set ups then you can just get a logger and tune with a safc.







#333

Just to be clear . . . to get the dsmlink I will need to buy an eprom ECU for 200-300 AND the dsmlink for $650?

With dsmlink would I still need a new AFPR?



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Originally posted by FlyinEsi
Just to be clear . . . to get the dsmlink I will need to buy an eprom ECU for 200-300 AND the dsmlink for $650? forums.2gnt.com/dcboard.php?az=show_topic&forum=12&topic_id=13280&mesg_id=13280&page= Current Status: HVAC Sent in

YUP. Plus a laptop.

dsmchip is only 90 bucks but u have to have 660's for it. Research both of them.






#333

Would i still need a new AFPR with the dsmlink setup?



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well yes to be on the safe side but some people dont need afpr to run with the walboro 255. I am one of them.

lol....buy a pda and get the software and cables from digitaltuning.com. DSMLink is some serious hardcore tunning. I was referring to pocket logging. Here is a website on the stuff you will need:

http://www.digitaltuning.com/index.php?pid=obdii

DSMLink is far better then the above method but as you can see it is very costly. YOu can also purchase the DSMChip that Remy is talking about which will help you out alot. If i were you i would get the logger and start loggin some runs and tune your AFC from there.

I would do the plugs and wires first. when it hesitates does it sound like a machine gun? If after doing the plugs and wires it's better but not totally fixed then your coil pack is on its way out as well.

I'm going to be changing the plugs and wires on Sunday, along with the starter :shrug needs to be changed. I will also have a new coil pack sitting on the side in case the problem is not fixed.



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