Advice - Suggestions?
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Author:  Spine [ Thu Sep 03, 2015 6:05 pm ]
Post subject:  Advice - Suggestions?

Hello all - I'm new (as of a few minutes ago).

A little history about me -

I'm an open source professional. I've helped develop open source programs in the past, and I strongly believe in open source - you get more people out there that can help, and you can help's a friendly community - people helping people. I'm anti-m$. They are the evil inside most computers. I'm a Linux person, always have been, always will be. However that doesn't say I won't be seen on a m$ system...unfortunately work requires it. I'm the System Administrator for a decent sized company.

Honestly, I HATE/LOATH computers. Often times I wish they never existed. I'm an old school mechanic. I enjoy working on the classics (before the introduction of electronics in your engines). I'm not afraid to get down and dirty on a good vehicle. When I was handed my first "ECM" controlled vehicle with a check engine light (1989 Buick century v6), it took me a week to figure it out. All I got was "Fuel Ratio Error" from the idiot light. After replacing the entire fuel system, it came down to the darn O2 sensor...I quit the mechanic scene at that time. I still work on classics from time to time, and I'll rebuild the computer controlled engines, but troubleshooting these computer controlled vehicles - count me out.

Now, I have this project that I accidentally stumbled upon and it's time to make it roll (on it's own power). So first, I'll give you a little intro.

About 9 months or so ago, I purchased these two Geo Storms. I call one Blue (1993 - Base model Isuzu 1.6L SOHC), and the other Yellow (1990 - GSI with Isuzu 1.6L DOHC). Blue ran great, new brakes, new tires, new...pretty much everything. Yellow was sitting in this guys back yard, all kinds of parts dumped inside it, flat tires, collecting even more dirt and dust with some rust. The guy was using Yellow as a parts car for Blue. He wanted $800 for the pair. I opened the hood on Yellow and didn't even hesitate with my reply - "I'll take'm".

After sitting in my back yard for a couple more months, I figured it was time to get Yellow going (Blue was a daily driver since the day we got it - awesome MPG). So, here is what has been done:

1.) Replaced all injectors
2.) Replaced fuel filter
3.) Replaced fuel pump

*** Was running great at this point with one exception - blown head gasket...was mixing coolant with oil, but engine performance wasn't effected ***

4.) Rebuilt top-end (hot tank, plane head for true, gasket kit for top-end, fresh paint for top-end+intake)

*** Drove it for about a week then the "crap" happened. Yellow acted like it jumped a tooth on the timing belt...back firing, missing, just all around running like crap. Took me three tries to get it up on ramps. Been there ever since and won't even try to start. Timing was dead on, so I replaced all matching electronic parts from Blue to see if I had any "dead" ones on Yellow - no resolution, so I continue with replacements...

5.) Replaced fuel pump and filter again
6.) Replaced fuel regulator
7.) Replaced coil
8.) Replaced induction coil (pickup coil in distributor)

Through all this troubleshooting, none of the fuses are blown, all relays worked fine (tested fine) all show proper voltage when the ignition is on and being tested (turning over, in run position, in accessories position), so I know the wiring is good. Fuel pump turns on when it's supposed to. Now, I have narrowed the issue down to the problem - which brought me to this forum/website. The ECM/ECU (whatever you want to call it - the brains of this engine) is bad (per the service manual via #8 above). I see one spark when I "turn off" the ignition, but does not spark when turning over (starting) or when "rolling" over (push starting).

So, that is my story - and this is my project. Now I know I said "troubleshooting these computer controlled vehicles - count me out", well that's for my customers and closed source setups. I'm excited to try this on my own vehicle - this is where I know what is what and why it's broke, vs. going against a stock GM/Ford/Dodge ECM which is a closed source setup.

Now, for the advice part -
What would you recommend for this vehicle? This will be my first attempt at building my own ECM. My second attempt will be my 1978 Suzuki GS1000 motorcycle with custom intake to make it fuel injected...but that's after I prove to my wife that this will work on Yellow.

I need it to run just the entire engine - the injectors, coil, and timing (with an output to the in-dash tach). There is no turbo so don't need to worry about that. I'd like to use the pickup coil in the distributor as the cam timing for the ECM.

Eventually I'd like to go with individual coils - one per cylinder, but that will be a future mod to get rid of the distributor cap unless it's very easy to do here. This vehicle is a standard, so I don't need to worry about any transmission inputs/outputs (and I wouldn't be taking on this project if it was an automatic - I hate'm).

So please, any input/advice is definitely wanted - but the advice to "dump it" or "it's not worth it" will not be accepted (on my part - my wife might see it and then say - "It's time to send it to the scrap yard"). One day I would like to do autocross with this vehicle, and having an open source ECM in the vehicle at launch time would help this concept.

Here is a link to the vehicle specs to perhaps assist in advice: ... storm.html

Here is a picture of the engine in this car (less the turbo): ... tgem15.jpg

Thank you all in advance...

Author:  Fred [ Fri Sep 04, 2015 6:42 am ]
Post subject:  Re: Advice - Suggestions?

My advice and suggestions are that instead of blindly replacing many many parts, you can validate what's actually wrong first, and then only replace what actually is. A scope is valuable here. You could have started with seeing no spark output, then validated the coil and ignitor functionality, then checked connectivity with battery ground and ECU, then looked at the RPM/position signal out of the dizzy and seen it make sense, checked the same thing at the ECU input pins, moved onto power and ground and signs of life stuff from the ECU and found it didn't have any, and stopped, without replacing a thing.

Strange looking little car. Tell your wife some guy on the internet has 9 cars and said your 3 or 2 or whatever are fine ;-)

As for an ECU, well, I guess you know which one I would recommend :-)

I've been out in someone else's one today, good fun.


Author:  Spine [ Fri Sep 04, 2015 9:39 pm ]
Post subject:  Re: Advice - Suggestions?

@Fred -

I guess I should have been a bit more specific on the parts replacement. I didn't "technically" blindly replace parts, just the parts that Blue didn't have that matched up and I did test the pickup coil - which was bad per the ohms via the service manual. So I took the parts (the ones that matched) from Blue and did a "swap" to see if it made a difference in either vehicle (with the exception to the fuel system and the pickup coil, with the backfiring it acted like a classic that was running too lean/rich or had jumped timing.

Yes a scope would have been more efficient, however I didn't have one at my disposal at the time I was originally testing (or any other time - I could not afford this expense for one vehicle as my wife would put it).

It "was" getting spark, and the timing was dead on - which is why I replaced the fuel system again. Now it gets no spark, but does have fuel (which is why I replaced the pickup coil - still no spark) - most confusing but narrowed it down to ECU issue(s)...

Thank you for your feedback Fred. I do hope to become a good contributor to this forum in the future.

Author:  Fred [ Fri Sep 11, 2015 9:23 am ]
Post subject:  Re: Advice - Suggestions?

Well, if the pickup coil as you call it was bad you wouldn't get fuel either, you'd get nothing. No fuel would be bad injectors, injector wiring, injector drivers, fuel pump, fuel pump relay, regulator, hoses/pipes, filter, etc. Ignition would be the usual dizzy parts + coil + ignitor + wiring + ignitor drivers.

You can get a cheap hand held scope for under 100 bucks these days, and with the amount of time you'd save, I'd say it could be worth it. I have a DSO quad, and I don't use it that often, but when I do, it's valuable to me. Those are around 200 bucks IIRC.

You're welcome, and we'll see what comes of it all, I guess! :-)


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