por4ever

Drove the car from CA to VA this week. Started out ok. Car was running rich but I noticed it started burning oil. The oil also stinks of gas. The first issue I am working on though is this. Engine developed an odd stumble. It will struggle at part throttle but if I get on the boost it will run better then back to stumbling on the overrun. Here is my troubleshooting so far.

1. TPS checks good as per Clarks garage.
2. Fuel pressure vibrates between 40-45psi at idle.
3. No fuel spitting out of fuel damper vac fitting.
4. All plugs covered in soot, #1 was fouled. Changed from NGK bp7es to bp6es since I was steady cruising. After 1.5 days driving checked again #1 had oily gunk surrounding post but gap not bridged.
5. Plug wires all ohm out at 2.9k, less then 6 months old.
6. Cap and rotor both look good.
7. Could see excess fuel in #1 cyl when cleaning plug today.
8. Changed FQS to pos 4 for +-0% retard timing as a safety precaution.

Car has Vitesse stealth MAF and chipboard and 55 lb injectors. Manual adjustable boost. Replaced O2 sensor a while ago with universal Bosch type.

Other then replacing the O2 sensor and replacing injector 1 I am kind of stuck. I know I should not have driven the car in this condition but I start school on Monday and I needed something to drive.

m73m95

Broken or seized ring?

por4ever

I put my hand over the oil filler and felt nothing. Not scientific at all but it was the best I could think of on the road. I plan to do a leakdown test as soon as I can get to the hobby shop on Monday or Tuesday. I don't hear any bad mechanical noises. No backfires or pops, no knocking or pinging, at least none I can hear.

Ziff951

Doesn't pos 4 on the FQS retard timing to -2.73* with no fuel adjustment? I had just done that to help lower my nox for emissions..that's the only reason I ask.. Best of luck to you!

I'm not a mechanic by any stretch, but could your head gasket be bad? maybe washing a piston between firings and forcing gas in the oil when under boost? Just spit balling...I'm sure someone knowledgeable will chime in soon enough...;-)

Ski

You may have a bad injector, easy to check if you can find a loaner or move #1 to #3 or whatever, see if the problem moves.

JohnKoaWood

Where in VA in your schooling? There are several of us out here who can help if needed.

Where is your MAF drawing it's power from? Power fluctuations on the 12V source can cause some issues.

Do you have a laptop with you to modify your fuel and timing tables if needed?

Do you have any way to monitor knock?

Any way you can have your injectors flow checked locally to you now?

Good recommendation above was to swap injector 1 and 3 to see if the problem moves... I have spare STOCK injectors, but am currently using my 55lb ers, not sure what anyone else out here might have sitting around..

bw993

You could have a vacuum leak after the MAF (i.e diverter valve). Are you losing coolant? If so, it could be HG.

por4ever

@JohnKoaWood I am in Norfolk. MAF voltage is another thing I was meaning to check. I can't remember where I am drawing the power from. I have a netbook but I am not using an SMT6 yet. I do not have a knock counter. I have not looked into anyone to flow check the injectors. I thought about swapping them but that is a little more then I wanted to get into on the side of the road.

@bw993 A possibility but in the past when I have had a vacuum leak I would get a slight bump as the boost gauge would cross into boost and I am not getting that now. Not ruling it out though. I will pressurize the system and check. I have done a venturi delete and replaced most of the small vacuum hoses with silicon. My heater control valve was leaking so I disconnected the hose and capped it. No coolant in the oil or vice versa.

I would also get a really strange smell from the exhaust. It smelled almost like an electrical fire and I was kind of hoping to find some evidence of it but nothing looks or smells bunt when I open the hood. Looked at the coil too in case it was leaking and just not giving enough juice to support a strong spark.

fast951

In addition to what others recommended already would start by checking the followings:

Items that can affect the overall rich condition:
- vacuum leaks (usually lean at idle and PT the rich on boost). If the car is running lean at PT, it'll stumble.
- TPS must be checked when hot - if it's sending WOT signal when at PT the car will run rich. I have seen TPS sensors working fine when cold, but go bad when they get hot.
- O2 sensor (unplug it to see if it makes a difference)
- Eng Temp sensor. Check this at the DME so you cover both sensor and harness in the same test. Again this test must be done when cold and hot.
- Bad ground causing the MAF to send a higher voltage. (Check voltage between black wire on unplugged MAF connector and battery NEGATIVE. Do this with ignition OFF and ON. If there is a voltage higher than 0.09Vdc, you have a ground problem).

Items that can affect the #1 cylinder running overly rich:
- Injector harness on #1. (swap connector between #1 and #2 injector)
- #1 injector is bad (Swap #1 injector with #2).

Cylinder #1 running overly rich may be the cause of the fuel smell in the exhaust. I would fix this first. If engine is still running rich, check the items affecting the overall rich condition.