3.6 Issues - I'm really scratching my head Options

[RiqueMar]

Hi There World!

Messaging the community here, as I'm thoroughly 'stuck' and I'm hoping someone has had a previous experience or perhaps point me in the right direction.

My car had been performing incredibly well. I probably put 1,600-1,800 miles on it driving back from Oregon. Yesterday, in the span of about 10-15 minutes it went from running and driving great to awful. I coasted down a long hill, and the engine starting dying and then immediately surging, like an on/off switch.

I eventually shut it down, but being only about 1-2 miles from my parents house made it back at a bit higher than normal revs. I believe a small bracket holding the Mass-airflow gave out and as a result, the air-intake lines / boots came disconnected. This made sense to me, as the engine was acting as if it might have had inconsistent air-intake / fuel mixture.

After fixing it - Over the course of the next hour, it went from bad to worse. I disconnected the battery, understanding this was a way to allow the ECU to reset, however now I cannot get the engine to 'hold' any level of RPMs.

Example, if I put my foot on the accelerator, it will rev-up-and-down about 400-600 RPMs. Likewise, I can hear and 'feel' the DME-relay 'cycling' on and off as I try to hold the accelerator / RPM level - I think this is very wrong as I think that one of it's responsibilities is the injectors. I've spent the last day to figure it out. Checked all my vacuum and air-connections as well as electrical. Tomorrow perhaps the fuel-pump. It's strange as for the last few weeks, it was incredibly reliable, 1-2 'stalls' under cold-start, but otherwise excellent.

I already missed 'having the car for my birthday' and hope to make it available for the 'Air and Water' event this weekend, so messaging other owners and the community is my last-shot before going to a shop. Any and all direction or previous experience anyone might have is greatly appreciated.

For communication purposes, I've done the following:
- Replaced the DME-relay - maybe slightly better, no change
- Made sure there's fuel - at least 3/4 tank
- Secured the Mass Air-flow sensor - no change
- Disconnected the battery, reconnected at different intervals (30-min, 60-min, overnight) - no change
- Checked all my air-lines / vacuum lines - no change
- (Earlier today) Added 1-qt of oil (why not?) - no change
- Checked the Flywheel position sensor - shook it, seems secure
- Checked the camshaft sensor - shook it, seems secure

[Maltese Falcon]

...might be good to check the small belt inside the dual distributor; also the condition of the cyl head temp sensor <<
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[Steve]

As Marty said, pull the bottom distributor cap off and make sure the rotor turns with the other rotor. If you can turn it by hand the belt is broken. Do you have the Bentley manual? There is a really nice troubleshooting section.

[RiqueMar]

...might be good to check the small belt inside the dual distributor; also the condition of the cyl head temp sensor <<
(IMG:style_emoticons/default/marty914.jpg)

As Marty said, pull the bottom distributor cap off and make sure the rotor turns with the other rotor. If you can turn it by hand the belt is broken. Do you have the Bentley manual? There is a really nice troubleshooting section.

Thank you both for the 'Late Night Tech advice'. Adding this to the list for tomorrow. This is all sounding 'stranger and stranger'. What appeared to be air-intake has quickly turned into a guessing game. I'm assuming by 'bottom distributor', we're referring to the dist. marked in blue as '2'?

** Edit: System won't let me add a photo, not sure why. I'm going to assume this is the Distributor 'closest' to the battery-tray.

[Cairo94507]

That is weird. My first guess would be the Mass Airflow Meter. When we were trying to fire my car, it would start and surge very badly, the exhaust pipe was dripping fuel and was very black. Unplugged the MAF and it smoothed right out. Cleaned the MAF and no change. Replaced the MAF with a new one and problem solved.

The rest of the issues we had, there were several, all involved wiring that prevented it firing. But you are well beyond that as you have almost 2K on the car so we know the wiring seems correct. The only other thing I can think of is fuel delivery- did a hose get kinked and is blocking fuel delivery?

Enrique, I hope you get this sorted so you can continue to enjoy your car before the next event. PS= Happy belated Birthday.
Michael (IMG:style_emoticons/default/beerchug.gif)

[mlindner]

Fuel pump up front, any chance you have a loose ground wire on the pump.

[Steve]

Regarding the fuel pump, I bought a kit at harbor freight that connected to the fuel rail with one of the included fittings. It helped me verify the fuel pressure. Check the link in my signature. It has all my troubleshooting problems. If your idle is hunting up and down, the majority of the time it’s the idle control valve. I tried to clean mine but it made no difference and I had to replace it.
The distributor closest to the battery is the one operated by the belt.

[SirAndy]

What year is your engine?
There was a recall on the '95 cars for the engine harness because the wires were melting inside the sheathing.

When it happened to mine, it started running rough first and eventually completely died. I got lucky and Bauer Porsche was able to get me the recall replacement harness for the recall price (that was some 15 years ago).
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[SirAndy]

What year is your engine?
There was a recall on the '95 cars for the engine harness because the wires were melting inside the sheathing.
When it happened to mine, it started running rough first and eventually completely died. I got lucky and Bauer Porsche was able to get me the recall replacement harness for the recall price (that was some 15 years ago).
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http://www.914world.com/bbs2/index.php?showtopic=80793
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[RiqueMar]

What year is your engine?
There was a recall on the '95 cars for the engine harness because the wires were melting inside the sheathing.

When it happened to mine, it started running rough first and eventually completely died. I got lucky and Bauer Porsche was able to get me the recall replacement harness for the recall price (that was some 15 years ago).
(IMG:style_emoticons/default/idea.gif)

Uff, I hope this isn't the case. My engine is the 964 variant which I think disqualifies it, all but positive it's 1992.

[Spoke]

** Edit: System won't let me add a photo, not sure why.

When I had photo issues it turned out that pictures from my phone were too big byte-wise. Had to reduce the size of the pictures then everything was ok.

Good luck with your engine. The 914 doesn't allow for too much elbow room in the engine compartment.

[ClayPerrine]

What year is your engine?
There was a recall on the '95 cars for the engine harness because the wires were melting inside the sheathing.

When it happened to mine, it started running rough first and eventually completely died. I got lucky and Bauer Porsche was able to get me the recall replacement harness for the recall price (that was some 15 years ago).
(IMG:style_emoticons/default/idea.gif)

Uff, I hope this isn't the case. My engine is the 964 variant which I think disqualifies it, all but positive it's 1992.

If the engine is from a 964, then how do you have a MAF? Those had the barn door air meter. The MAF would require a separate module to convert the MAF sensor readings to the proper signal for the ECU.

That may be your problem. Do you have the Vane air meter (barn door air meter)? If so, swap it in and see if the problem goes away.

[Chris914n6]

Unplug the idle air control and see if it stabilizes.

Less likely but my FI did funny things when the battery was low and on it's way out.

[Justinp71]

I'm not a 964/motronic expert but familiar with EFI. If its a MAF not a AFM maybe it got damaged when it fell off? I suppose the AFM (barn door air/fuel meter) could get damaged too. Sounds like symptoms of a bad sensor potentially.

Is there a TPS sensor on those? I had a car that something fell and pushed the TPS out of calibration, just had to move the TPS back to home position. But it ran wacky like this when it got bumped.

Nice car btw... I was checking out your build thread, very nice!

[RiqueMar]

Thanks so far everyone, keep em' comin'!

Correction on my terminology, I have an AFM / Air-Flow Meter, I was just using the wrong terminology.

[ClayPerrine]

I'm not a 964/motronic expert but familiar with EFI. If its a MAF not a AFM maybe it got damaged when it fell off? I suppose the AFM (barn door air/fuel meter) could get damaged too. Sounds like symptoms of a bad sensor potentially.

Is there a TPS sensor on those? I had a car that something fell and pushed the TPS out of calibration, just had to move the TPS back to home position. But it ran wacky like this when it got bumped.

Nice car btw... I was checking out your build thread, very nice!

The TPS on a 964 is a simple switch telling it the throttle is either closed or at wide open.

[wndsrfr]

Thanks so far everyone, keep em' comin'!

Correction on my terminology, I have an AFM / Air-Flow Meter, I was just using the wrong terminology.

BAD GAS...drain the tank & fill with fresh.

[rgalla9146]

Thanks so far everyone, keep em' comin'!

Correction on my terminology, I have an AFM / Air-Flow Meter, I was just using the wrong terminology.

BAD GAS...drain the tank & fill with fresh.

Bad Tank... drain the tank and look for rust and crud.
My 'coated' (very poorly) tank went bad in two years.

[RiqueMar]

Thanks Guys, but skeptical in this case even though that is sometimes the culprit.

Tank has been ‘gone through’ when it was at the shop in the last few weeks, as well, the day before I had filled with fresh gas and have been driving probably 1600-1800 miles in the last 3-weeks.

While, yes, a possibility - I’m skeptical in this instance.

[Justinp71]

I had the issue when I first fired up my EFI my fuel filtering was not the best and started plugging up some injectors. Also there was a bit of grit that came off from the new an6 fuel line threads and got to the injectors. I pulled the fuel system all apart, cleaned the injectors and then installed a Deutchwerks fuel filter. When I reassembled everything I used a drop of oil on the AN threads and if the threads did not go on right away I pulled apart the fittings and recleaned.

My build ran fine at first too until all the bits got to the injectors.