The car:
96 ESi - ATX
*stock rebuild w/ .020" over
*5angle
*valve train upgrades (lifters, rockers, springs, etc.)
*CAI
*4-1 header (wrapped)

The problem:
*intake backfire (at start up and shut down)
*generally shitty idle (very lumpy, active misfire)
*grey/white smoke from exhaust (very dense, seems to continue to "pour" out of muffler for a good minute after shut down)
*definite unburned fuel in exhaust (stong odor)

Attempted remedies:
*new coil pack (OEM)
*new plug wires (Accel)
*swapped out known good plug wires
*swapped out known good plugs
*used the search
*replaced fuel filter with 54k+ miles

Observation...
*Plugs had been gapped to .025", adjusted gap to .035"
*When checking plugs, #4 appeared to brand new, while other three had consistant carbon deposits
*Compression test of this cylinder yielded a solid, cold 180psi
*Car ran strong for better than 300 miles after rebuild

At this point, I'm suspecting timing jumping on him, but I'd rather get a couple reliable people to concur before I advise my friend, here, to tackle that nightmare.

Please advise. Thanks for playing.

When you say "This cylinder", did you mean that you only compression tested the one?

Yes we only checked the one , I had just checked all of them two weeks ago and we asumed since that was the cylinder that had the clean pulg that was the problem cylinder. Hindsight we probaly should have checked the rest.

If that were the case I am pretty sure that all the plugs would of been dirty...

I am gonna say that your next bet is gonna be to inspect the timing belt. The only other thing is defective EGR but I don't think it would effect it that much.

Well I just had the injectors cleand and bench flowed.I cleand out the intake befor I installed it. So those are out . As far as the cat its only got 55k on it I would hope it would last longer than that but it is a dsm lol. I do have a minor leak where the down pipe meets the cat. what sucks is that it seemed to get worse the more we dicked with it .I think it just might be the timming because I know I should have but I didnt replace the tensioner when I did the rebiuld so that could be the culprate.

www.partsdinosaur.com

Have you checked that all of the injectors are firing? If one of them is dripping badly or is completely kicked all sorts of weird things can happen.

2016 WRX STi Limited (current)
2001 A4 1.8tqms (donated)
1991 GVR4 #1933 (sold)
old.dsmregistry.com/detail.php?carid=218 (dismantled)

Get a piece of clean vac hose that you can stick into your ear(po mans stethascope). Start the car and put the other end of the hose right next to the injectors. They make a ticking sound.


95 Eclipse RS : 5 speed
15.7 @ 87.9mph
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

The intake backfire indicates a lean mixture. Since you have 1 clean plug then lets go to that cylinder. Poss injector failure.

Granted now you are running on 3 cylinders, how is the vacuum. If the timing jumped enough to cause a misfire at idle then you would have codes in the ECU. our timing can be pretty far off before the motor begins backfiring. I would know i had cam issues when the new motor went in.

It doesnt hurt to check the timing but i dont think that will be the problem. If it was the 4th plug would not be clean.

Sticking exhaust valves will do this will cause the backfiring. or what sounds like backfiring. Pull the VC to verify. Since you now have a very lumpy idle it is possible.

Terry

Not to beat a dead horse but when my coolant temp sens went out I had horrible intake manifold backfiring and the ammounts of unburnt fuel we're simply out of control. Lots of smoke and a horrible idle.

And aren't our plugs supposed to be gapped to .45-.5....not .35?

Just a couple of things that you probably already looked at but...
Did you pop your plug wire for number 4 so you could isolate problem at that cylinder? Does engine run fine otherwise, or is there problem all the way thru? Obviously, leave off wire to see if it changes anything while bringing up RPM. Yeah, timing is a good thought and I presume that you checked marks to see if you slipped a tooth. A thought (that is not too happy a thought) would be a sticky valve. Could have been a tolerance situation on a valve or valve guide or rocker etc. Anything that will allow that valve to stick open just a little. This can fit in the description of "it ran fine for the first 300 miles". That could be the amount of time it took for the valve to start binding. Did you do a cold comp test? If you did that could also allow the great comp numbers. With THAT being said you could also do a warm comp test and the valve may not stick at that point (the rpm of the starter may not be at the sticking point). One thing that does bug me about this is that even with a sticky valve, you would normally shows signs of some kind of combustion chamber explosion.
Well, food for thought.
MB

Oh yeah, are there consolation prizes available?

Well we think we isolated the problem. It seems the the #4 injactor is stuck open .We checked timing and it was dead nuts so we went back to the top end . There we found by listening to the injectors that the #4 wasnt making any tapping sound like the others and a multimeter test showed that electricly it was good but we belive that it is just stuck open and soaking the plug . So the new question is will 30lb injectors work on a realitively stock motor, because I have a set avalible to me right now. please let me know thank you.

Today we installed a fuel pressure gauge to make sure his pump isn't the problem (needed to be done anyways) and he's getting a solid 55-60psi out of it on his stock fuel system. Pump = good.

We then dropped the motor a bit, yanked the crank pulley, and checked his timing. Everything lined up perfectly. Timing = good.

Then, our 4G63 friend showed up and finally got to hear the car running. We were talking about listening to the injectors to see if they were all working. Seems like #4 isn't doing anything and we suspect it to be stuck open. We actually listened to it with a mechanic's stethoscope, which was pretty cool, and it wasn't clicking at all.

We ohmed the injectors out and they were all within spec to the Chiltons, but when we pulled the connector on #4 and then started the car, it ran just as it had before. 55-60psi of fuel just shooting right through that one, we're betting. We had a lot of raw fuel (still atomized, I might add) pouring out the muffler even two minutes after killing the engine.

As a final test, we slipped a thermocouple under the header wrap on each runner of the header. Once running for a couple minutes (if you can call it that), we were getting a consistant 250* on the surface of runners 1,2, and 3, but 4 was only hitting about 150*.

Raw fuel out exhaust, 100* cooler surface EGT, and no noise from that injector leads us to believe he needs to replace his injector(s). Sad thing is, he just paid $60 to have these cleaned and tested not two months ago. They all tested out to be at 98% or better.

QUESTION:
Can he use 30# Ford MoSport red tops on an otherwise stock fuel system without any problems. I want to think he might be able to pull it off, but I'm not sure. If he can't use them, we'd like to know. If he can't use them, I'm sure he's not wanting to buy them from me, but if he can, this could be a good, temp fix until he gets paid again. At $2.65/gal, he's not liking having to drive 100 miles a day in his Chevy full size.

Thanks.

30# injectors more than likely are going to be to large running the stock fpr. I think that it will run very rich especially and idle.

I have a couple sets of stock injectors laying around, so hit me up and I will send a set to you.

Joe
MFG Racing

95 GS
MSnS
FP3052 coming soon.


http://www.dsmregistry.com/detail.php?carid=1107

http://www.cardomain.com/id/95turbogs

What about the accel 24 or 26lb injectors?

Really anything over stock is going to be to large running stock fuel pressure.

Joe
MFG Racing

95 GS
MSnS
FP3052 coming soon.


http://www.dsmregistry.com/detail.php?carid=1107

http://www.cardomain.com/id/95turbogs

Well fine then lol. Then what are are stockers I thought they were 24lb

The stock ones are 19lbs.

Joe
MFG Racing

95 GS
MSnS
FP3052 coming soon.


http://www.dsmregistry.com/detail.php?carid=1107

http://www.cardomain.com/id/95turbogs

So If I were to get an adj fuel presure gauge would they work then?

Alright I got my injectors cleaned and back in and now it still smokes and stinks to all hell (like bad emisoins)and I am pulling a air temp code, I have gotten this code before and replaced the sensor and it went away but its back . As far as the idle it got better when I put the injectors back in but now it has a random sputter . Anyone have any ideas. please let me know.