Please help me diagnose this problem
Please help me diagnose this problem Recently my car is missing really bad under WOT and any situation where the car is under a load - ie taking off from a stop. Under full throttle it cuts out....pop, pop,pop - like when traction control kicks in (I already thought to turn that off of course). I scanned the car and there are no codes stored. I have narrowed it down to a fuel delivery problem I think. I suspected bad gas so I got a fresh tank of 94 at Sunoco and it seemed to improve but it still cuts out. I have a new fuel filter ready to install. Anything else I should be looking at? If it was spark related....plugs, wire, coil....it would throw an SES code right? The car runs perfect under nowrmal cruising but does idle a bit rougher than normal. This did start happening all of a sudden and there are no unusual mechanical sounds....clicking, banging, etc. The guy who computer tuned my car is going to scan it with HP tuners as soon as I get over to his place sometime this week I just wondered if there was something else I should be looking at.
I know I'm a n00b but is there any unmetered air leaking in past the MAF? My car was running like yours when my fernco slipped off at the TB and air was getting in after the MAF. No SES light either.
Sorry I did not respond - I was not able to get on here today. It was tuned right after the cam, headers, and pulley in May. The guy who did the tune has already said I need to bring it by and he will scan it and see what is going on - I do not have the data logs. I was just checking to see what else I should do to track down the prob.
Another thing I thought of was to check your grounds in your engine compartment. On my WRX I had loosened a bolt holding a bunch of stuff to a ground point but forgot to tighten it. My car ran like crap and my datalogs were showing random TPS ranges from -10% up to 110% no matter what the actual throttle position was. Just another thing I thought I'd throw out there.
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Verdad Gallardo Still fightint this "intermittent" missing problem.
Done:
1) new fuel filter
2) Had the car scanned with HP tuners by the guy who tuned it. He was picking up the miss but scould not pinpoint why. Most of the time it was running perfectly - getting full 28 degrees of timing at WOT - A/F looked good, MAF seemed to be working fine. When it "cut out" it was picking up knock and cutting timing but I cannot find the source of this miss.
It runs strong 95% of the time then it will just cut out - will not stall or anything but just does seems to "skip a beat" - at WOT it will back fire from time to time. I have new plugs to install but I am running out of ideas. (Coil packs - fuel pump - ??)
Done:
1) new fuel filter
2) Had the car scanned with HP tuners by the guy who tuned it. He was picking up the miss but scould not pinpoint why. Most of the time it was running perfectly - getting full 28 degrees of timing at WOT - A/F looked good, MAF seemed to be working fine. When it "cut out" it was picking up knock and cutting timing but I cannot find the source of this miss.
It runs strong 95% of the time then it will just cut out - will not stall or anything but just does seems to "skip a beat" - at WOT it will back fire from time to time. I have new plugs to install but I am running out of ideas. (Coil packs - fuel pump - ??)
FormerVendor
Joined: Aug 2005
Posts: 531
Likes: 0
From: Decatur IN.
hi...im a tuner in fort wayne IN.We have had a bad rash of deisal gas that was pumped into the high octane tanks at a local sunoco...Including one brand new (1200 miles)lingenfelter 382 ,a pro street opel with 434 s.b.c not to mention some of the areas best street racers ,just a hint that it not always the car...look at everything thing that had happened prior to the foul up
cheers..
cheers..
Staging Lane
Joined: Jul 2003
Posts: 62
Likes: 0
Here's some ideas:
1) Check if any of your plugs is cracked.
2) In a dark garage, start your engine and while the car is running, turn on the A/C and work the TB blade to rev the car. Look for sparks or arcs around plugs, wires, coilpacks.
3) Spray QE Electronics cleaner into your MAF. Don't touch the wires, just spray them with the cleaner. Let dry and re-install.
4) Check your fuel pressure under load.
5) Pull 4* of timing in the RPM/load areas where you notice the problem. If it clears it up, then add back in 1* at a time until problem starts again, then back off 1* of timing in those areas.
6) Run some Redline fuel system cleaner thru the car. Whole bottle in a 2/3 tank of gas. Do some "spirited" driving and do not add any gas until almost completely used up.
7) Run a can of GM Top-End cleaner thru the TB, while the motor is running, and working then throttle blade to keep it from dying.
1) Check if any of your plugs is cracked.
2) In a dark garage, start your engine and while the car is running, turn on the A/C and work the TB blade to rev the car. Look for sparks or arcs around plugs, wires, coilpacks.
3) Spray QE Electronics cleaner into your MAF. Don't touch the wires, just spray them with the cleaner. Let dry and re-install.
4) Check your fuel pressure under load.
5) Pull 4* of timing in the RPM/load areas where you notice the problem. If it clears it up, then add back in 1* at a time until problem starts again, then back off 1* of timing in those areas.
6) Run some Redline fuel system cleaner thru the car. Whole bottle in a 2/3 tank of gas. Do some "spirited" driving and do not add any gas until almost completely used up.
7) Run a can of GM Top-End cleaner thru the TB, while the motor is running, and working then throttle blade to keep it from dying.
Last edited by queso; Aug 24, 2005 at 02:48 PM.
