I noticed something weird today when driving back from San Jose in my 10th AE. It started when i was accelerating smoothly back to the speed limit after traffic cleared. All the sudden my car fell flat on its face, popped, then took off like a rocket! I then noticed that the tach needle was bouncing and when ever it went low i had NO power, causing the car to buck wildly. It was uncontrollable, yet the wideband didnt show anything wrong! According to it i had been running about 10.6:1, and the temp gauge was right in the middle, where as usually it hovers near the bottom. I got to the side of the road and after looking at my fuel pressure gauge, it was WRAPPED to the OTHER side of the pin. I took it off, busted the glass, moved the needle by hand, and now it works again. Also, i checked for vacuum leaks, and could find none.

After all that i got back in the car, and it worked fine like nothing had ever happened!! I think it was due to cooling back down again, but i dont know. My car was idling at around 1500 rpms, and had been with no problems until this happened. So, being about 200 miles from home, i got back in the car and drove off. It worked perfectly for another 140 miles or so, then when going up a slight hill out of placerville, it did it again! I was even being careful to stay out of boost, but it changed nothing. Then i did the same thing, pulled over, checked the fuel pressure which was at 38 static, let it cool, and got back in and was fine the rest of the way.

When i got home, i checked the TPS, which was at 1.34, so i put it back, adjusted the timing (which was 1/2 inch from the mark ), and tried it out, and it worked flawlessly, full boost and everything running about 10.8:1 AFR.

WHAT WAS WRONG?/STILL IS WRONG? any ideas?


OH YEA, and BTW> I tried to adjust the idle, but even when the car was warmed up, it wasnt touching the stop screw and was still running at 1500!!! When i moved the timing, it barely dropped below 1000, but still, why is it not touching and idling normal? the TPS is set up correct, as it the timing. Thanks!!!

 

my GUESS: check the ground to the ECU, while this may not be 3800 rpm hes, it kinda has the same attributes. check your secondaries as well. dunno about the idle.

 

Okay, it did it to me again today....5 TIMES!!!!! The last time it happened i was out infront of my house. When the tach would drop the wide band would go REALLY REALLY REALLY LEAN. I pulled over, and the car wont even stay running, but i left the key on. I opened the hood and the fuel pump relay was CLICKING like a clock, only three times faster!!! I was listening around while it was clicking, and the secondary injectors were attempting to fire too!!! I checked my ECU ground under the throttle body elbow and its fine, clean too!

WHAT IS WRONG???

 

Oh yea, and another thing. It only does it when its WARM, and only some times. I drove it all day and it didnt do it till i was on my way home. If i shut it completely off and let it sit for about 5 minutes then its fine for a while.

 

Maybe the crank sensor is shorting out? I remember my friends car had a haltec and you could see in the log when the rpms would jump up to 12k or something like that and then back to normal once in a while.

 

it cant be that though because the fuel pump relay is CLICKING on and off. So are the secondaries, that is why my wideband says its really lean when the RPMS drop quickly.

 

Is the tach needle going low cause it's turning off? If so your trailing coils are going on and off. I would check your ecu ground.

 

i checked my ecu ground and its good, it has a clean mounting spot and i fully connected

 

it cant be a problem with the ECU right? I would think if it was an ECU hardware issue it wouldnt be an intermittent problem. Any Ideas? What all has to do with the fuel system turning on and off?

 

maybe the coils are going bad?

 

check the primary and secondary resistance of the coils using a ohmeter (the multimeter have this feature). For the problem that you are talking about sound like the coils are the cause. Take the meassures and compare it to the resistances that the repair manual says.

 

okay, i checked the coils and they are within spec. The resistance is below 1, so im good there.


Could the ECU be bad and thats whats causing it to turn my fuel pump solenoid on and off really rapidly?

 

The fuel pump is controlled by the ECU. I would suggest you to find the fuel pump relay and test his condition. If is good, maybe the problem is in another place, like the ECU. I dont know if the CAS (electronic ignition with pick up coils) can cause that. Would be good to you to find infotmation about troubleshooting the CAS.

 

sounds your on the right track in finding out what the problem is. Sounds like an electrical short, vibration disconnect, loose ground. Id check out your fuses like your EGI fuse to see if any of them are starting to turn really dark brown.

 

i checked the fuses and they are all perfect, kinda a silver/golden color. Would it help if i chained a bunch of grounds together so that the ecu ground had more points to attach to?

 

no, that would just clutter up your engine. if the ground is clean and well connected it should be fine. i wouldn't rule out the ECU, test it to be sure. A new (used) one isn't too expensive.

 

The problem is i would have to change the injectors out to try another ecu because its an Rtek. I took sand paper to my ECU ground today, along with the mounting location, and even the bolt until they were clean and shiny. Just incase i tee'd into it and added 2 more grounds so that if one isnt clean it will go to the next....hopefully....I drove it today and havent had any problems yet, but it didnt show up imediatley before either.

 

hmmmm.... man..... if the secondaries are firing while the thing is sitting there, and the fuel pump is pumping mad crazy, it's like the car thinks that you are WOT all the time. Wierd. Check to see if the TPS is in spec. My vote is still on the ECU though.

 

you can data log with the Rtek's though can't you? that should help determine what's up as well.

 

yea, i know the car is turning the fuel pump on and off, and i know the secondaries were clicking when the car wasnt running, but still turned on as the fuel pump was clicking in unison.

I also know that when the RPM's drop, the car leans out BAD! and thats why it drops. Im talking about off the wideband kinda lean, stalling the engine temporarily. when the fuel pump relay turns back on it was floodingly rich.

 

it did it again last night!!!!!!! AHHHHHHHH!!!! Okay now that its out of my system, what else should i check??