Zirconocene

I'm just now getting back to getting my '90 S4 figured out for the current no-start. I looked through the @Michael Benno sticky on the various technical updates and manuals, but there's nothing I can find for a test plan explicitly for a 1990. Is such a thing available, or does the plan fall under one of the previous model year's guide?

Thanks

The Forgotten On

It has the same systems as a 89 as far as the engine goes, bypass the catalytic converter protection system (clear relay near the computer) and it is the same as any S4.

So feel free to just follow a standard S4 no start guide!

Zirconocene

OK, that is what I needed to know.

Many, many thanks!

Cheers

Mrmerlin

Umm, what was the last thing you did prior to the engine not running?

Zirconocene

The last thing I did was set off the alarm by opening the hatch with the car locked. I've pretty much eliminated the alarm as causing the fault, and Mike Benno and I went through some of the diagnostic checklist, but came to a point where it wasn't clear if the plan we were using was applicable to the '90.

We tried the LH and EZK from the GT with no luck, tested voltage and continuity on a few plugs, and then sort of ran out of steam.

I'll document things on my no-start thread, I just wanted to make sure the list I'm going though is appropriate for my model year.

Cheers

Kevin in Atlanta

Your no start is actually a start and die, right?

So, you have fuel and spark momentarily.

Is that correct?

Zirconocene

@Kevin in Atlanta : That is correct. There is the briefest hint of the car cranking over, then it dies.

Kevin in Atlanta

So, not a classic no start.

And you touched nothing before this started happening. Moved the car is all, right?

A monstrous air leak can produce those symptoms. Make sure the MAF is seated and the hose to the manifold on the DS is tight.

If you want to diagnose then you need noid to test injectors, a fuel pressure gauge on the rail to monitor fuel pressure and a spark plug test light to verify you have spark.

And make yourself a relay jumper to jump the fuel pump relay. Jump the relay and listen for the fuel pump. Try to start the car with the jumper in place.

Pull the fuel pump relay and fuse and inspect their contacts. Look for any corrosion in the fuse. Replace with a new one if you have it.

Not sure the typical replace the relays will help.

My thinking is that you get fuel pressure and then you don't. Could be a plugged fuel filter, a failing fuel pump or dodgy CPS.

Good luck with your testing.

Mrmerlin

Did this car ever get the intake refresh that I suggested?


NOTE before removing relays and jumpering them.

Quick test you should test to see if they are working,
kneel down at the CE panel and put your finger on each of the starting relays
X bus,
Fuel pump,
LH,
and EZK relays turn the key on and crank it you should feel the relay clicking,
if you dont then dive deeper.

NOTE other quick test,
spray ether into the intake see if wants to start. this isolates what your missing

Zirconocene

@Mrmerlin : No, prior to difficulties with other projects and my daily driver, I was hoping that was going to be the winter project year. It's still on tap, just delayed.

I plan on digging back into this issue this weekend, and I'll post some updates.

If any of you are ever out this way, beer (or your favorite beverage) is on me.

Thanks

Mrmerlin

Ok keep us posted where are you located

Zirconocene

I'm just south of Portland Oregon these days. Mike Benno and PorKen are local to me, as well as some other folks on here, that I've only spent limited time with.

Mike started a little get together this past year that, hopefully, will turn into a Frenzy-like gathering. We might have to split time between Portland and Seattle to get as much of the PNW hooked into the kind of culture that's going on back on the east coast.

Cheers

FredR

Are the EZK and fuel pump relays energising OK when you try to start?

Zirconocene

Hi Fred-

Indeed, the EZK and fuel pump seem to be getting the juice they need. I've tried starting the car with the fuel pump relay connections jumpered, and there was no luck.

I'm leaning more and more to what Kevin said, above, and will move onto those items (fuel pressure, vacuum, CPS, etc.). Proactively, I found some new ignition control modules for a relatively inexpensive price (I hope, one order from a vendor already cancelled on me) and will swap those in prophylactically, but after I run through some of the more systematic testing. I need to educate myself on some of the testing of individual components (like those modules, or the CPS), so as to avoid throwing parts at the problem, which I'm already starting to do.

Cheers

Gary Knox

I'm sure this is a stupid comment, but I'll show myself as an idiot anyway. Frequently when a vehicle is killed by the alarm system, rebooting puts everything back to position. Thus, re-lock, then unlock the car. If 'no go', then disconnect the battery ground, let system set overnight and re-attach. Then, maybe, lock and unlock again.

As Worf woud say - Occam's razor!