Thanks for taking the time to read.

Background:
I have a a4 96 Z28 with 117K miles. I drive the car on weekends and it's not a daily driver so I don't drive it that much. Last year I put in a new opti, headers, new plugs, new wires, new fuel filter, new 02's. The waterpump is two years old. After header install, I threw in a 160 stat for my pcm tune and program for early fans & firm shifts. I still have original coil, icm, maf & egr. The car meets its scheduled maintenance regarding oil changes & I use 91 gas. The Z has been riding perfectly fine until Thanksgiving weekend and I was a lil rough with the car but nothing too much.

Problem:
Got off the freeway and came to a stop, as soon as I got going again the car started to sputter and lose power. I was able to get it up to speed but was struggling. I was afraid to come to a complete stop so I rolled and limped it home until I had to stop at a stop sign and it died. Started up again and then died. Wouldnt start.

Troubleshooting:
Next day the car started right up. The idle was actually perfect and I let it warm up. I placed the shifter in gear and seemed to be fine. I drove around the block and then it started stalling, then died. Wouldnt start at all...kept cranking..

Few days later, the car started right up. The idle was fine and I let it warm up. I placed the shifter in gear and it sputtered and died. Wont start at all...kept cranking

Today, started the car and it idled perfect. I swapped the MAF and I warmed the car up. I put the the shifter in gear and it was still idling fine! hmmm
I was actually thinking of a test drive until I noticed this whole time that the fuel pump BUZZ I usually hear in the rear wasn't heard at all? I let the car idle a lil more as I walked around the car and when I got back in the car I noticed the Temp was starting to climb higher than usual. It was climbing past 220 for some reason ..no big deal..so I turned the car off and then tried to re-start the car...nothing, dead. Just cranking... now I'm confused.

Assistance:
So with this information what tests should I be conducting? I tried swapping MAF's, PCM's & fuel pump relay. I checked various sensors and wires for appropriate connection and I'm out of ideas to try. Shoot me some ideas so I can formulate a checklist to troubleshoot with.

Thanks.

Mike

 

Is the SES light on. I had a similar problem with my car. It ended up being a Coolant temp sensor. There are two on the car, one on the head and one on the water pump. The one on the water pump is the one that is hooked to the computer. That is the one it would be. However it could also be a broken wire on the MAF. I would have some one scan it on a computer to see if the MAF is reading to less or much CFM. But I'm no guru.

 

no ses light...I have a Autotap scanner but not really good with it.
If this means anything, MAF At idle the rate was 1 to .9 lb/min. I have no way of testing the car on the steet to run parameters at load since the car dies. I've already towed it twice so the driveway it stays.
My waterpump is somewhat newish...maybe 17k on it. It came with the sensor so I would think it should be fine.

 

Thats prob right on the MAF. It is prob okay. But I replaced the Coolant Temp sensor and it went out again about 2 months later. But if it was that it would prob give you an SES. Check your airbox to make sure you didn't suck up a bag or something and check the fuel filter.

 

Go back to basics the computerized controls rarely make cars not start. You need fuel pressure and injector pulse to allow fuel into the engine. Spark to ignite the fuel and at the proper time. You should be able to hear the fuel pump prime for 3 secs when you turn the key on. Pull a plug wire off and check for spark.

 

I dont hear any priming from the fuel pump.
When I'm unable to start it....I would pull a plug to check for spark but theres no way to get my hand in there....especially when its hot.

 

I went back out to the car and started the car and it barely started as I had to pump the pedal lightly to keep it going. After a few seconds it picked up pretty good and started to idle fine again like if nothing was wrong.
After 5 minutes I put the car in gear and it was holding idle. Few moments later... it died and it restarted once this time but then died shortly after. After that..no start agian.

I know nothing about Autotap so here's a Injector pulse width at idle..I was able see a readings of around 3.20's ms..what ever that means. I'm using a handheld palm for the readings and this is a pain in the ***.

I just came across Injuneers parameter write-up page. I'm ganna have to read it so I can get a better handle on this scanning.

 

Fuel Pressure? Get a gauge and put it on the shrader valve.