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Discussion Starter · #1 ·
Hi! Thanks in advance for any help.

I have had my 1990 Plymouth Horizon TBI 5 speed for a little over a year now. When it starts, it runs great! Unfortunately it has been through 3 ECU's now. I got tired of trying to find what was causing the problem and I have tried to bypass the ECU entirely. This is the forum I have been following: 2.2/2.5 ignition mod w/Bosch 009 distributor

I pulled the TBI off and the old distributor out. The vw distributor and chrysler "cog" went together fine and are installed. I made an adapter plate to fit a Weber 32/36 on the TBI intake.

When I turn the key, it starts up as soon as I turn it. It stumbles very roughly before stalling and sometimes backfiring through the carb. I don't have the fuel lines hooked up as I am planning on converting to a mechanical fuel pump, so I filled up the carb bowl and spray carb cleaner or squirt gas in it with the throttle held open before I start it.

All 4 cylinders have healthy spark. Since there is no ECU, the coil is wired (coil to ballast resistor, to fuse box, to switched ignition).

Please let me know what you think is going on. It won't run for more than 3-4 seconds so I can't check for a vacuum leak or set the timing. I have worked with carburetors a few times on a few different vehicles, but nothing like this. The rough running and backfires through the carb is concerning. Thanks again!
 

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Welcome To TD!!!

I cannot help with your conversion, however, engine controllers are usually damaged by excess amperage in a circuit.
What fault codes were stored in memory that led you to believe the controller was at fault.
 

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Discussion Starter · #3 ·
Welcome To TD!!!

I cannot help with your conversion, however, engine controllers are usually damaged by excess amperage in a circuit.
What fault codes were stored in memory that led you to believe the controller was at fault.
Hi! Thanks for the reply. The first time it wouldn't start, I had it towed to the mechanic a few blocks away from the parking lot I was in. After a few days, he called and said it would need a new ecu. We ordered one, and it ran great for a few months. Next time it wouldn't start, I was at home, so I did the diagnosing myself. The car would turn over but had no spark or fuel. I replaced the auto shut shutdown relay and nothing. The ecu was still under warranty so I exchanged it and it ran great again.

So that's the ecu that was in the car when I bought it, and now 2 replacements it's gone through. Non of them have ever given fault codes other than 11, 12, and 55.

Now, with the new points style distributor, I have spark. I tried leaving the tbi on with the computer, but it still doesn't send a signal to the fuel injector. I even wired the fuel pump direct to 12v just to test and nothing.

I'm thinking there must have been a massive vacuum leak when I tried the carburetor the other day. It's off for now while I try to figure out what to try next.

I can't find a 2.2 carbed intake anywhere. I'm not sure that would solve my problem, I just don't know if these carb adapters are reliable in terms of seating everything properly.

Trans-Dapt 2025 Carburetor Adapter Amazon.com: Trans-Dapt 2025 Carburetor Adapter : Automotive
Brown Wood Fixture Gas Wood stain
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Just so you are aware, Code 11 is a code, on 85-87 models the code description is...
"Engine has not been cranked since battery disconnect".
Once the engine is cranked the code goes away.
The most common problem if the code does not disappear after cranking is due to a faulty HEP ( Hall Effect Pickup) or a problem in the HEP circuit, the HEP provides a crank/ rpm signal to the controller, if the signal is not present the controller has no idea the engine was cranked.

My 40 years of experience tells me you probably had an easily fixable go mom issue with the HEP circuit.
 

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Discussion Starter · #5 ·
I replaced the hall effect before buying the new distributor. Nothing changed. No permanent changes have been made, so I could always return to "normal" if necessary. I would just need a new distributor because I had to disassemble part of the original to use on the points style one.

Nevertheless, I would prefer the carb and points distributor setup for simplicity sake. I have nothing but positive experiences with my carbed vehicles and so-so experience with my fuel injected vehicles. (Clogged injectors, ecu issues, etc...)

If it matters, my fuel economy was pretty low compared to the epa ratings. The line holds pressure so there is no leak.

I think I'll give the carb another try in the next few days
 

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Contact member 4 L-bodies
 

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Discussion Starter · #7 ·
I will try to contact him. Thanks!

I have a busy work week, but I've ordered a rebuild kit for the carburetor. I also realized that the ballast resistor might be bringing the voltage too low since the plugs were a bit wet with gas upon pulling them out.

The current plan is to leave it alone until I can get the carb cleaned and rebuilt. I will then bypass the ballast resistor temporarily to see if that solves the rough misfiring idle and stalling. If it is able to run long/well enough for me to be able to use a timing light, everything should fall in to place 🤞.
 

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If it does not work out for you, I am interested in the distributor you put together.
 

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Discussion Starter · #11 ·
If it does not work out for you, I am interested in the distributor you put together.
I am still waiting for a few things in the mail, but the more I think about it, the more I realize what went wrong. I believe after I get everything put back together, it will fire right up.

Check out the link I posted in one of the earlier posts to see how to fabricate one. It only took 30 minutes or so. Here is the distributor I bought:

Kuhltek Motorwerks 0231170034 https://www.amazon.com/dp/B00QXXCBTQ
 

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I'd say to put a gas jug beside it and feed it with a proper pump.
Check for any air leaks too.
How certain are you of the carb?
 

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Discussion Starter · #14 ·
Quick update:

I rebuilt the carburetor and found one of the idle jets was missing. That was probably a large part of the problem. A replacement will be here next week. I also ordered a pertronix ignitor and 12v coil so I can run 12v directly from the ignition switch. I think weak spark was the other problem because the ballast resistor was keeping the voltage around 6v.
 

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Discussion Starter · #16 ·
Another update:

The Pertronix ignitor and coil came this afternoon. The coil slid right in. The ignitor plate however, had to be cut to fit around the vacuum arm. (If you use the 009 non vacuum distributor, it won't need cut). It's not too bad of a job if you've got a sharp hacksaw blade.

Despite the battery almost being dead from previous cranking, the spark looked pretty strong!

Tips:

If you want to run 12v straight to the coil, buy the 3 ohm coil.

Don't use an angle grinder just to be safe and not overheat the unit if you have to cut the ignitor plate.
 

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Uh question & I maybe way off & shot in the dark with all the other stuff---I went on line to ck if vehicle had timing belt & info claims it does. Have you checked the timing belt condition & timing--tooth missing frayed belt causes all types of problems
 
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