Injected CSL odd running condition

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corsachili

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I've got a very strange symptom in a CSL I recently assembled and am trying to get running. The engine will start, and run for about 5 seconds, and then die. It won't ever run for more than 5 seconds. My first thought was fuel, because it acts like it's not getting enough, or that it's completely fuel starved. I put a fuel pressure gauge on the hose feeding the rail and it's got a solid 30PSI until the engine dies, so it's not the fuel pump. The fuel injectors are all newly rebuilt and calibrated.

I swapped out the ECU, main relay, manifold press. sensor, a complete distributor, the coil, and the throttle position sensor with good parts (out of my own, running CSL). None of these cured the behavior.

Other strange symptoms are that the throttle is totally unresponsive during the precious few seconds that it runs, and that the brake booster hose nipple, which does not have the hose connected to it, is drawing air. If you put your finger over the nipple the engine dies immediately. I removed and inspected the throttle body and found nothing awry.

It seems electrical, as if the wiring harness or a bad ground, or frayed wire is preventing the trigger points from doing their job.

Does anyone have any bright ideas as to what I might be missing?

-tj in Los Gatos
 
Starts but she won't run ( for very long)

1. Air leak; enough to seriously cause it to lean out based on your brake hose symtom.

2. AFM- turn on the switch, prop the door open and listen for the combo relay switch and/or check for voltage at the pump. Alternately jump the relay to make sure the pump has juice and enough of it. Typically at start, there's a little more than when everything is on and running.

You didn't call out what f.i. version you have and if anything's changed.

There's an excellent article on the first five's faq board for trouble shooting early systems.
 
TJ - It sounds like you have fuel, air and spark necessary to start but something just shuts the engine off. Does the D Jet (is that what the CSL used?) use the Fast Idle Air Bypass auxiliary air valve? I read that this is connected to the cold start injector by an air hose. Possibly a short here that is shutting down before the warm up is completed.

Good luck.

Doug
 
Apologies to all for the lack of information. The engine is a stock 3.0L with stock Bosch D-jet fuel injection.

The interesting thing is that it doesn't feel/sound like it's getting any air through the throttle body. With the brake booster and aux air valve disconnected it runs poorly, but if you plug both orifices the engine dies. D-jet does use a Manifold Pressure Sensor, and yes, the main relay and cold start relay both have 12v to them, and you can hear them click on. I've even swapped both parts out, with no effect on the problem.

I've also jumped the fuel relay to make sure that it remains running all the time, and the problem persists.

Also, disconnecting the cold start injector has no effect on the condition.
 
Perfect description of a bad or disconnected afm.
Start with a pin-out and then try a borrowed afm
I think you will find that your injectors are not getting enough signals to let the car run.
 
Hi Don,

By AFM I assume you mean the Manifold Pressure Sensor? It's a newly rebuilt part from Fuel Injection Corporation. Further, it works just fine in my car, and when I installed the Manifold Pressure Sensor from my car in the poorly running one, the problem persisted.

TJ
 
Is that the one I picked up for Terry?
Robert has had some problems with those.
 
D Jet

Your problem is that the engine is only running on the cold-start injector. Probably caused by incorrect wiring around the starter, early & late cars have different wiring in this area. There is a transparent connector in the injector loom, check the wiring against a diagram as this is the main 12v injector feed on early models.
Also check you have connected the single white wire (with black covering...) from the ECU loom close to the distributor to the 12v side of the ignition ballast resistor.
The later cars do not use a ballast resistor, as it is built into the actual wire.
Also check the main injector earthe on the rear plenum support bracket.
 
Hi Tj,

Did you remove that cleaning rag from the plenum? Sorry, could not resist...I would not think the MPS is at fault even if defective, check distributor/coil...do you still get sparks 5 seconds after cranking?

Gerrit
 
Roundel-
Can the engine run just with the cold start injector? I thought that this provided additional fuel to what the main injectors were supplying at the cold start time. So, if the car is running well for those first 5 seconds all the injectors should be working?
 
cold start...

I think it would provide enough fuel for a not so cold cold-start (as in TJ's garage), easy enough to disconnect in order to confirm or eliminate.
 
D Jet

The 6 main injectors are controlled by the distributor points, the cold start injector is controlled by the cold-start relay / water temp sensor, cranking system. Completeley different things.
 
Agree with Roundel- Have you checked for FI signal?
 
relays

TJ, I do not know if your CSL has relays, but on a M6 I owned it drove me crazy with a similar problem, did the relays, cold start, total electronics, etc...come to find out it was a bad relay from the get go...the new one was bad.
 
Yes, the main, cold start and fuel pump relays have all been swapped out and checked. We did a bit of diagnostic work yesterday (thanks Terry) and found a couple things, but nothing that points to an obvious failure. One thing that I do need to understand is how to set the advance cam that actuates the Throttle Position Sensor. It's in the housing behind the TPS, which is part of the throttle body. The throttle body had been disassembled prior to me getting the car, and I've never had that piece apart, nor have I seen how one should be set. There is no diagram of it in the Blue Book as far as I can tell.

We found that the #6 fuel injector is not firing. There's no continuity from the ECU connector to the fuel injector connector, so the car is only running on 5 cylinders, but that's not enough to cause the "run for 5 seconds and then stop" symptom. I'm going to clean the connector at the ECU and tighten the female connectors and see if that helps matters. It did look pretty crusty there.

-tj in Los Gatos
 
D Jet

The injectors fire in banks of three, so the problem must be specific to that injector / local wiring. One injector will not stop the engine from running, so there must be another problem ??
Position of the throttle switch will not cause this problem.
 
D Jet

For the engine to run for 5 seconds there MUST be a spark !

No vacuum problem will ever stop it from running for more than 5 seconds.
 
roundel said:
For the engine to run for 5 seconds there MUST be a spark !

No vacuum problem will ever stop it from running for more than 5 seconds.
Click to expand...

Although the subject of this post was entitled "odd running," it might be better described as unable to achieve "sustained operation." For an engine to run for five seconds there must be a source of ignition. I hardly dispute this notion given my observation that brief running "also suggests that your ignition is an unlikely cause of the [immediate] problem." Nevertheless, a few chaotic sparks from a poorly functioning ignition system hardly makes for sustained operation of a "relatively" modern engine.

Similarly, as noted, vacuum may not be essential for getting an engine to fire intermittently. However, it is indispensable for sustained operation of the subject engine. The Djet's design employs a pressure sending unit. That specialized and calibrated unit, is absolutely dependent upon manifold vacuum to function. Hence, sufficient manifold pressure is a requisite for sustained operation of any d-jet equipped engine.
 
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