Well, the car left me stranded for the first time today.

Luckily, a friend of mine's dad owns a shop so it was just a phonecall to get the car flatbedded back to school.

Problem started when I left the gas station, car would sometimes cut out while driving. Once I got to my destination after that (short <5 min drive) the car's idle was bouncing from basically 0 to 1500. I didn't let it do that for very long. 20 minutes later I came back to the car and started it up, same bouncing idle stuff...and unable to rev it up. Giving it any throttle usually resulted in stalling.

Things tried:
-unplug AFM
-unplug TPS
-unplug 1 injector
-kick DME/KLR
-wiggle crank sensor connectors/wires
-check for vac leaks (initially seemed like just a huge vac leak like an IC pipe blowing off...but then the problem magically fixed itself)
-R&R/hit DME relay for ****s and giggles
-fuel pressure OK (gauge on rail)

Eventually after either wiggling the crank sensor connectors/wires the car started up and idled and drove well. I pulled away and a minute later, the same problem. This time it was just wiggling the crank sensor connectors/wires that got it going...but only to start doing the same thing again a minute later. At that point we called it quits and loaded it up on the flatbed.

I currently have the DME/KLR sitting on the floor because I just installed some chips and the Zeitronix wideband and will be installing the SMT6 shortly. They've been sitting out for about a week while I've been using the car, I dont think this has any effect but it's a possibility.

Probably about 5-6 times in the past 2 years I would go to start the engine and would get no bouncing tach, a little wiggle to the crank sensor connectors/wires would resolve that quickly.

At this point I am leaning towards either DME or crank sensors. The DME was obviously just opened recently to do the chips, so its possible that had something to do with it.

Both crank sensors were replaced 3 years/20k miles ago before the engine rebuild...so I would like to think that they are not the problem.

So if anyone in the area has a DME/crank sensors that they could let me borrow....I would really appreciate it. I have no mode of transportation, but I'm sure I could get a friend to drive me around to meet someone somewhere.

Any other suggestions are welcome....

thanks,
Adrial

 

*bump* for the legit question

 

I'm not sure about your car, but on the early NA the speed/reference cables have a connector right in the center at the back of the engine (I'm not talking about the Micky Mouse ears where they mount). It's just a plastic "plug" with little clips snapping it together. If the problem (briefly) changes when you wiggle them, I'd check that connector. Mine was partially unclipped and it caused problems identicle to yours.

HTH.

 

I'm taking a long shot here........ Have you checked around the j-boot, really close. Why I ask..... this time of the year, is hell on rubber parts. The freezing conditions, then warmed up to over 100 in just a few minutes. The j-boot could have a slight leak in it, that is expaning as it warms up. Like I said, but a long shot. I know you wiggled around the crank sensors, and it started and ran fine for a minute, but that could have been a fluke. Based on a couple of cars with bad j-boots, and a 951 being even more sensitive, it could be a leak around it. But..... it could be the dme. The bouncing tack is what kills the j-boot suggestion.

 

Did you try the diagnostic connector ?

 

Well, if messing with the reference sensor helps then that is probably your problem. I had a very similar problem, however my car would cut out between 2-3k rpms under low load. Pulled up the reference sensor to find that the shielding was melted through in numerous places. The sensor itself was literally two months old, however my neglect to properly locate the wires when installing it was the problem (I assume it was hitting the downpipe or crossover). I would get a flashlight back there and look at the entire length of the sensor's wiring to see if something similar happened.

Also, I have that damaged sensor laying around and believe it or not the wiring is easily long enough for the melted section to be cut out and re-wired, so if you want it let me know and I can grab it next time I am home.

I highly doubt a vacuum leak that you can not EASILY recognize would cause such an issue. It is possible that the AFM is on it's way out however.

 

I replaced the coil and have discovered some more about the problem. I pulled back the rubber boot on the crank sensors on the DME side and everything looks fine.

Everything runs great when it is cold, but as the engine comes up to temperature it starts to cut out more and more. Eventually it gets to the point where the engine will start but not run as was described in my first post.

Jiggling the reference sensor cables does nothing, hitting the DME/KLR does nothing. I don't really know what to do aside for start replacing parts. If it comes down to it I can borrow a scope and look at the output from the crank sensors and go frm there.

thanks for any help,
Adrial

 

Determine if the Dme drivers are excessively hot when the cars shuts off.

 

I expect that overheating injector drivers would cause the DME case as a whole to feel warm? If so, no it feels fine.

Although ever since the rebuild I have noticed the injector drivers being audible, which was not the case before.

The DME was opened to change the chips back to stock during the rebuild, so it is possible that the traces are wearing (resistance increased)...thus asking the injector drivers to work harder. However, like I said the DME is not hot.

I just noticed something new. Before the car would start to cut out too badly, if I would let it engine brake down to idle...it would sometimes kick the injectors on too late...causing the car to buck badly.

thanks,
Adrial

 

Yes, take the cover off so you can feel the driver itself.
Young whippersnapper.

 

Couldn't really identify the injector drivers...didnt really know what I was looking for except that I figured there would be a pair of them. Nothing in the DME got hot though. The circular object on the side with a heatsink got warm, but nothing unreasonable. The noise that I heard was in fact the injectors themself, not the drivers. A grommet between the pass. area and the engine wasn't fully installed after the engine rebuild...hence I could hear the injectors in the car.

The car acted a little differently this time though. I would be at part throttle at 2k and all of a sudden the engine would start to slow down as if I let off the throttle. I could still hear the injectors firing, but the wideband showed full lean. So, that leads me to the fuel pump....which to my knowledge has never been replaced. I am going to give that a shot tomorow.

Any thoughts?

thanks,
Adrial

EDIT:
whooaaa on inspection of fuel pump prices...
$200 from paragon, $230ish from NAPA...
I see lindsey has an upgraded pump for $170...anybody know of any others?

 

although mine is an early NA...this sounds very much like when my fuel pump began to go....utimately I started swaping parts until I was at the point of pulling my hair out...all the while, the fuel pump would run/make-noise so I never suspected it. When I finally broke down and brought it to my mechanic it was the fuel pump ( motor was running but not enough pressure being pumped). A new one was the cure!

 

I have a good one you can borrow to elliminate the possibility.

 

J berk, that sounds encouraging...thanks.

Sounds great ST.
I am in NJ (08854) right now, would you be willing to ship it?

 

OK...so!....

Fuel pump got changed...problem is different now.

Fuel pump appears to have made a difference...

Now, it took longer for the problem to present itself....and once it did I could unplug the AFM and TPS and get the car to idle steady at 1500.

I am going to check the sensors out more tomorow

But for now, its my birthday and we're having a party tonight so I'm going to get trashed

Just thought I'd give a little update