laxsex

I inherited an 88 924S from my grandpa. He stopped driving it due to it having a fuel issue. Exactly what that fuel issue was, I dont know. So I went over to his house and tried to start it. It cranked but would not fire up, but it would run on starter fluid.

I found that there was no voltage at the fuel pump with the key on, or with it cranking. I used be multimeter to check that the ground circuit, and it tested to be ok.

So I started to search around on this forum and found out about the common failures of the DME relay. I installed a new relay, and still no voltage at the pump, so I took the relay out and jumped it on terminals 30, 87, and 87b. Then the pump ran. But still the car would not start.

I have fuel at the fuel rail, but after cranking, I removed one of the plugs and it did not have fuel on it.

Tomorrow I am going back to his house to test the injector circuits with my home made noid light. I know that I have power to the injector.

I'm assumming that the DME computer controls the ground for the injector?

If I find tomorrow that the injector circuit is ok, then what route do I take?

If the injector circuit is not ok, is it safe to assume that the DME computer is to blame?

Any help you guys could give me would be wonderful. Thanks, Jacob

laxsex

Today I checked out the injecters. The injectors are not firing. This leads me to believe that the DME is to blame.

I took the DME out and inspected all the solder joints and did not find any broken joints, but I went ahead and resoldered all of them anyway. After re-installing the DME, the injectors will not fire. I'd like to see if I have continuity between the DME and the injector ground, what pin on the DME controls the injectors?

Am I correct in assuming that the DME is the problem? Does anyone know where I could get a hold of another DME.

I was under the impression that the car was an 88 924S, but the part number on the DME that I took out of the car was 944.618.121.04

From searching around here I found that the PN for an 88 DME should be 944.618.121.05

So what gives?

Sam Lin

The injectors could be stuck shut from sitting. Pull the rail out with injectors still in it, and point it upwards and crank, see if all injectors fire.

Sam

laxsex

That is a really good idea. When I tested the injectors i used a homemade noid light that connected in series with the injector. The light flashed, but was very dim. Leading me to believe that the DME is either supplying a poor ground, or the injectors are stuck closed like you said.

Can I clean the injectors at home, or can they be sent out to be cleaned. Or is cleaning out of the question

Lee Zook

Make sure that the flywheel position sensor conectors at the rear of the camshaft housing are pluged in correctly/tightly. There are 2 connectors/sensors. I believe that the plugs look the same and are interchangeable, but it won't work if they are not pluged in correctly. I had one of the connectors work loose once. The car had similiar symptoms that you describe. Once I found the connector issue and pluged in tight, it started right up.
Good Luck,
Lee

whalebird

look at the fuses and, also replace the dme control relay under drivers side dash. common problem. a noid light with a 12volt bulb will apear dim because the voltage is supplied in pulses. in my experiance a 12 volt noid light that is dim means good injector fire.

dgz924s

The fact it will start on starting fluid suggests an air/fuel issue rather than an electrical one. If it fires you have fuel and spark. How much gas is a possible culprit though.
Give all the vacuum lines a good look and make certain the AFM is not sucking in air around the TB and/or AFM ports. Many AFM j boots are cracked and do suck in air in turn causes improper mixtures/readings,hard starts.

Look at........fuel pump check valve....filter and FPR.

GL Dal

WitchHunter

Did you verify that the rail has fuel pressure? The injectors seem to be getting a pulse to open. That just leaves the injector itself.... As Sam pointed out, it very well be that the injectors are stuck closed.
We see it all the time with cars that have been sitting or with injectors that have been removed. Having them professionally serviced will most always bring them back up to spec.

Gordon
WitchHunter Performance
Fuel Injector Cleaning & Flow Testing Service