Good Evening-
I have a 1985.5 944 that ran fine until 3 weeks ago. This was when I swapped out my stock chip in my ECU with a Russell Berry Max HP Chip. I drove it 30 miles, no issues, but took it slow. I parked it in my garage, and two hours later, this is my situation. I tried putting the old chip back in, same result. Russell was kind enough to send me another DME to test with, but the same issue remains. It cranks hard, smells of gas and doesn't even seem to be trying to fire. I will paste a copy of my PCA tech help correspondence:

Looking For Another Set Of Eyes To Help Troubleshoot My 1985 944 No Start

07.29.2016 Asked by Wesley Powers [NST]

1985.5
944
Mileage:
65,000
Engine 2.5 8v
Saint Paul,
Minnesota

This is likely a long shot, but I am looking for some help with my 1985.5 944 with a sudden no start issue. I have gone through everything on Clarks Garage, and am confident that it is a lack of spark. I can short a plug directly from the coil and I get spark with the ignition in on. It will turn over just fine, but I am getting no spark past the coil. I have 2 different coils (both worked before this), and two sets of wires. Neither seem to be the issue. What I don't have is a fuel pressure gauge to test for sufficient or excessive fuel pressure, nor do I have an oscilloscope for the speed and reference sensors. I can smell fuel, but there is no even partial start...

Other things I have checked:

Multiple DME relays

Multiple Ignition relays

2 fuel ignition relays

2 distributor caps

I am looking for any thoughts

I apologize for the rambling post,

Wes Powers

313.530.3153


Comments
If you are getting spark and
Submitted by George Beuselin... on Fri, 07/29/2016 - 19:16
If you are getting spark and fuel, it may just be that your rotor under the distributor cap is not secure (meaning that the 4 mm allen bolt or the 8 mm hex bolt has backed out and the rotor is loose on the supporting base.)

That said, there are a couple of tricks to isolate the source of your problem.

1) Watch the tach as you attempt to start the car. If the tach is bouncing during the start cycle, you are getting a good signal to the coil. If not, the common causes are the flywheel sensors or the DME relay.

2) Go to NAPA and get a noid light for your car. Disconnect one of the injector plugs from an injector and have someone watch it while you go throught the start cycle. If it pulses, you can eliminate the flywheel sensors and the DME relay from the list of suspects.

Of course, it is also possible that your ECU has gone bad... it happens... these parts are thirty something years old after all. If you know a PCA member who has the same year and model as your car, remove your ECU and take it to a running car and plug it in. If that car will now not run, thats the culprit.

I'll close by saying that not having the test equipment to diagnose this problem by yourself merely means that you will have the opportunity to rent someone elses diagnostic equipment, one expensive hour at a time.

reply
George-
Submitted by Wesley Powers [NST] on Fri, 07/29/2016 - 23:09
George-

As in the past, thanks for your help. I will have to grab a noid light, the spark tester needs a friend in my toolbox.

Tach IS bouncing, but only about 3mm? (from my web searches, it looks about right)

As for swapping ECUs, I unfortunately don't have that option.
I tested the rotor, and it seems secure.

I appreciate you taking the time to help

-Wes Powers

313.530.3153

follow-up
Submitted by Wesley Powers [NST] on Sat, 07/30/2016 - 21:04
George-

I borrowed a Noid light set, I AM getting pulses at the injector harnesses when I crank the engine. I am really hoping this isn't my ECU.

Anyone in Minnesota or the surrounding areas that has an ECU I can try?

-Wes
313.530.3153

Does anyone have any suggestions? I have tried a second DME from Russell Berry, same issue

 

[IMG]

 

I am sure there are thoughts out there regarding troubleshooting...Don't be shy

 

It could be the ignition switch. They're known to cause random, odd and/or intermittent problems. Usually they develop a crack in them.

 

snb13
I have one on order, I was hoping to avoid that route, but I agree that it is looking like the next step. Thanks for your input
Wes

 

It's not a terrible job to change it out.

 

An engine needs 4 things to operate: fuel, oxygen, compression, and ignition.

Noid light...confirms ignition while cranking. Pull the rail...fuel at the injectors while cranking? How old is the timing belt? Does the engine sound/feel normal when cranking? Regardless, pull the front cover to make sure it is still intact.

 

Of course you mean ... confirms injection pulse while cranking.

The four things that are needed are: compression, air, fuel, and ignition (at the right time.)

 

Good catch...correct, that's what I meant. I should probably refrain from answering questions after a long day.

As the air we [and your car] breathe contains ~21% O2, I suspect your issue is fuel, ignition, or timing. Ergo...

1. Pull the rail...fuel spray at the injectors while cranking?
2. Pull and ground each plug...adequate spark while cranking?
3. Pull the front cover...timing belt intact? Cam properly timed?

Let us know what you find.

 

I might have missed it but did you check the resistance of the speed and reference sensors, as per Clarks garage procedure?
http://www.clarks-garage.com/shop-manual/ign-02.htm

 

Definitely confirm it isn't speed and reference sensors. Either find someone with a car you can borrow from, find an oscilliscope, or buy 2 of them and just replace them (you can find aftermarket ones online for 20 bucks a piece, I was having an issue and tearing my hair out and instead of bothering to go through all the trouble of testing them I just bought 2 new ones. Solved all my problems, and the quality is fine). Cranking fine but not starting definitely sounds like S&R's

 

Delayed response, I have been travelling.

I had WEAK spark, but spark at the secondary, I had moved on to the ECU. I will copy a list of what I have changed:

 

Hi Mike-
Sorry for the delay, I replaced them both. Please see my attachment word doc below