gingy

Hey, all
This is my first post here, so I'll start by giving a little back story. I'm 17, and picked up a 928 a couple of weeks ago. I've done quite a bit of work on it so far. But, it will not idle. The only way it will run is with starter fluid, or if I disconnect the Mass airflow sensor. I have cleaned all the plugs, replaced the fuel pump, and filter as well. I also tested the relay for the fuel pump, and used a noid light to make sure the injectors are getting signal. I am getting fuel and spark because it idles at 2,000 rpm when the airflow sensor is disconnected or if the door of the sensor is propped open. I just bought a new MAF online, and I'm still having the same issue. I am pretty good with engines and repairs, and doing all the work on it myself. Any tips or leads in the right direction would be greatly appriciated. Thanks in advance, guys. It's great to be part of the club.

Mongo

Welcome to the forums!

Just a quick check, can you confirm there are no breakages in the air flow meter harness? Contacts for the grounds should be as clean as possible. Check the ground locations for the L-Jet ECU and clean. Sometimes, a corroded ground can cause all sorts of running issues. While this may not be the solution to the problem, it will definitely help the way the car runs later.

Some of the other experts will chime in here shortly. Good luck to you.

gingy

Thanks for the reply!
As far as I can tell, there are no broken wires. Now, Where would these ground points be? And, I was also wondering if I could stick a multimeter in one or two of the 5 pins that run to the MAF to see if it was indeed getting signal from the computer.

Mongo

Here is a diagram of the ground points. I'm not sure if the grounding locations are different for a 16-valve 928 compared to a 32-valve.

Hope this helps.

soontobered84

Andy, there are differences, but this should get him started anyway.

Tomkat80222

As a noob, I can't offer any help except SEARCH. All your questions have been answered before.

Mongo

On a side note, someone on this board had been chasing down running issues for several months. I have a link to one of his threads that tells what the solution was. The car was a 1981, but it was also an L-Jetronic car like yours.

https://rennlist.com/forums/928-foru...k-to-life.html

Check your engine temperature sensor wiring also.

gingy

I couldn't find anything that was my actual problem, even with 12 tabs open on the matter.

soontobered84

Gingy,
When you say you bought a new one, was it really new, or was it just new to you? These things get out of calibration, but can be recalibrated pretty easily. search for threads regarding the recalibration. Also, it may be under "barndoor" and not MAF, since I don't believe it's really a MAF.

Good Luck on your project.

Mongo

Another helpful link for you when it comes to troubleshooting your problem:

http://nichols.nu/tip540.htm



Also,With the new AFM installed, will the car start and run with your foot on the gas?

gingy

New to me, yes. When I bought it, it was supposedly "tested" to be working. And, thanks for pointing my in the right direction.

gingy

It runs with starter fluid only when it is plugged in. It will run for about 5 seconds at maybe 100 rpm, just barely hanging on.

Mongo

It would be worth taking the plugs out of the car to inspect their condition after the attempts to run it.

Also, did you replace the relays with NEW ones?

soontobered84

Sounds like the injectors need to be cleaned/serviced etc, but REPLACE the fuel pump relay, the fuel injection relay, AND the ignition relay with NEW relays FIRST.

That can save you a lot of time and grief.

gingy

To see if they're wet, I presume?
And, no. I tested them with an ohm meter, and a 12V power source. No relays replaced.