HELP for a friend. race in 3 days.

[James Mallon]

this is for a friend in desperation. he is in WA if anyone can help?
William Yu

Guys, we're starting to freak out, our race is in 3 days and we still cannot figure out why the engine runs like ass.
So what it does is when I drive the car more than 20 minutes, then it starts to run sluggish and if I give any gas the car starts to misfire really badly and just won't fire at all and just dump fuel. I have to be very very very gentle on gas and it would barely get it self going at highway speed.
We thought this issue was related with the car temperature, but it might not. We have an open thermostat so the car runs to like the coldest point on highway, nomatter what temperature it is in (cold, warm, normal temp) if I drive more than 20 minutes it would do the symptom.

Some mentioned that it is my camshaft position sensor, or coolant temp sensor ( one for gauge one for ecu) I replaced all 3, car has rebuilt head, new injectors, new plugs, new plug wires, new coil packs etc. Still runs like ass and our race is very soon. Please help us throw any information that you could offer. Thank you.

 

[zoomlater]

Were there any codes

 

[jayro]

Were there any codes

x2. The time frame could be when the ECU switches out of open loop and starts using input from other sensors.

Step one is to pull the codes.

Question, why are you running no thermostate. The stock system, thermostat included, is more than capable of cooling the engine in track conditions. Not sure if this happens on the SHO, but no thermostat can contribute to inefficient heat transfer out of the radiator since the fluid will be moving too fast....something to think about.

 

[rubydist]

it sounds like the engine coolant never gets to operating temp. in that situation, the pcm will run open loop (startup conditions) for 20 minutes. after 20 minutes, it will go to open loop even if the coolant temp is still low (thinking that the coolant temp sensor must be bad).

it sounds like your engine will not run closed loop. your post-20-minutes symptoms suggest there is a problem with intake air temp sensor, tps, or mafs. I would look for codes and be looking in that area for problems.

I also agree with the above - I would most definitely put a thermostat into the system like it is supposed to be.

 

[luigisho]

X3. Looks like sensor malfunction at first glace. Codes will help point the way

http://web.archive.org/web/20090917070939/http://www.shophoenixproject.com/eec/eec.htm

 

[BaySHO Performance]

I presume that the race is the 24 hours of Lemons at The Ridge. Let the guys know that there will be another SHO there as well that might be able to help them, at least to pull and interpret codes. They should already be there as they were in Vancouver, WA early this morning driving North. Look for this car:



'Team Dick' #39 in this pic. Now 'Up In Smoke', #714. I did most of the work putting it together.

What year is their car, and what front brakes are they running? I've heard a rumor that it's a '90 running the stock 10.2" brakes. If so, they will have to be EXTREMELY gentle on the brakes. They will warp within 20 minutes otherwise.

If they need advice, they can call me on (408) 363 3551. They should leave a message as I don't pick up unknown callers.

 

[BaySHO Performance]

this is for a friend in desperation. he is in WA if anyone can help?
William Yu

Guys, we're starting to freak out, our race is in 3 days and we still cannot figure out why the engine runs like ass.
So what it does is when I drive the car more than 20 minutes, then it starts to run sluggish and if I give any gas the car starts to misfire really badly and just won't fire at all and just dump fuel. I have to be very very very gentle on gas and it would barely get it self going at highway speed.
.

Too late unfortunately, although they did get 14 laps in...

I've only just twigged that this sounds like a vacuum leak to me. I had these symptoms coming back from the
SHO Shop once. A couple hours in it started to run rough and would fall flat
on its face if I tried to give it anything but a little gas. I had to pull
over to the side of the freeway. Luckily it was an easy fix: the air hose
clamp at the TB end had been left loose. So they should check the clamps for the air hose and MAF.

Starter fluid will also pick up a vacuum leak as the revs will go up when sprayed over likely leak points,
including the intake couplers which may be cracked.

 

[BaySHO Performance]

One more thing: Mike Stimson of SHO Source who has been helping them mentioned they were having problems with the IAB (Idle Air Bypass Valve, bolted to the intake just inboard of the throttle body). If they had occasion to remove the sandwich plate between the IAB and intake, they may have reinstalled it backwards. There's two pipes for hoses pointing down on the sandwich plate: the pipe going straight down should be at the front, the pipe that curves inwards towards the center of the sandwich plate should be to the rear.

If so, they would have had trouble installing the intake as the hoses would get in the way. So it's possible that the intake isn't properly installed, and the vacuum leak is there. Somewhat unlikely as the rough running would begin as soon as the engine was started, but worth a check.