Car runs on two cylinders.

[1990whitetsiawd]

Ok, so here's the story about six months ago my car was only running on two cylinders so i figured that the coil pack was bad so I bought one that was known to be good. That fixed the problem for a while. Then like a month ago car started running on two cylinders again so I figured that the coil pack that I bought second hand went bad. So I said whatever and left the car alone until this week when I bought a brand new coil pack from extremepsi, just put it in the car and it won't even start now but I pulled plug wires to check and see if they were arching and only number two and three were 1 and 4 aren't getting anything. So i think that it must be the power transistor. Right? Ideas. I know the computer is booting up because the check engine light shuts off after 5 seconds. And I know it's getting fuel because the afpr is saying like 40.

 

[twicks69]

Check your cam angle sensor and your ignitor.

 

[1990whitetsiawd]

Ignitor thats the power transistor right? The cas I am pretty sure is good wouldn't it throw a cel if it was bad or not because I am odb I?

 

[bpestilence]

I'd be willing to bet that it is the transistor. I used to use DSM transistor in cars that I built MegaSquirt for, but I dicovered that they liked to burn out with anything more than a stock ignition. Since then I have switched to high voltage ignition transistors that I found on Digikey.

I ran through the "only firing on two" scenario for a long time on my Turbo Rio. I even tried using performance Accell coilpacks. Everything burnt out because of those transitors failing.

 

[1990whitetsiawd]

So I tested the power transistor per my haynes manual for a 1990 and I got a negative 1.2 for both the 2-3 and the 1-4 senders. So this would be pointing towards my cas as being bad correct?

 

[1990whitetsiawd]

Replaced the cas today. The car runs but only on starting fluid once that burns off and you try to feather the gas it stops running, and it only runs on two cylinders once again and thats with the new coil so I guess I am going to buy a new transistor, that should hopefully fix my problem.
Maybe the coils were never the problem and it was just the transistor all along?

 

[1990whitetsiawd]

So I ordered a new transistor about two weeks ago waiting on jnz to ship it out. But I have been messing around with the car the last week or so again, and have come to the conclusion that the injectors are not firing and am not sure why this is. They have power at the clips but they won't fire. I also keep getting a tps code as well but when I turn the key off and then back on it clears and comes back after trying to start it. Thought that it would be stored. I am pretty sure I put the cas in right. But I'm thinking that I would get some fuel even if it wasn't installed right because it would still send a signal. Because if the ecu injector drivers were shot wouldn't that make it not have power at the injector clips?

And I know that you are suppose to have that temp sensor in the bottom of the radiator installed as well. But ever since I have owned my car I had a fluidyne in it without that sensor and it has run before without so maybe that is some weird possibility of why it is not starting now I am not sure.

Any suggestions I wanna drive my car.

 

[BUCK]

Because if the ecu injector drivers were shot wouldn't that make it not have power at the injector clips?

Absolutely NOT - check your ECU - The Temp Sensor at bottom of Radiator Passenger side is for the Fans ONLY, to the best of my knowledge the ECU gets Temp feed from the Temp Sensor at Thermostat Housing.

 

[steve]

I have been messing around with the car the last week or so and have come to the conclusion that the injectors are not firing and am not sure why this is. They have power at the clips but they won't fire. If the ecu injector drivers were shot wouldn't that make it not have power at the injector clips?

So which is it? Power or no power at the injector clip?

If you look at the MPI diagram you'll see that the injectors get power from the MPI Relay by way of the Injector Resistor on the firewall. The power goes to a common connection for all the resistors and each resistor connects to an injector. The other side of the injector is connected to the ECU. You should see battery voltage on the wires from the Injector Resistors and the Injector should all measure about 3 ohm resistance. When everything is plugged in you should see battery voltage at the 4 pins from the injectors at the ECU too until you start cranking the engine and the ECU tries to fire the injectors.

 

[1990whitetsiawd]

I took my digital volt meter and am getting about 11 volts at the injector clips. That is with the black test lead grounded and just using the red test lead to plug into the injector clips. So this would mean that the ecu is good right? I don't really want to put my eprom in until I figure this out so I don;t risk the chance of messing that one up.

 

[Nvisabl]

Absolutely NOT - check your ECU - The Temp Sensor at bottom of Radiator Passenger side is for the Fans ONLY, to the best of my knowledge the ECU gets Temp feed from the Temp Sensor at Thermostat Housing.

ECU sends ground to injectors voltage is constant. Sounds like an ECU to me.

DJ

 

[steve]

I took my digital volt meter and am getting about 11 volts at the injector clips. That is with the black test lead grounded and just using the red test lead to plug into the injector clips. So this would mean that the ecu is good right? I don't really want to put my eprom in until I figure this out so I don;t risk the chance of messing that one up.

You saw 11v on both pins or just the side going to the injector resistor?
Did you measure the injector resistance and if so what was it?
When was the last time you charged the battery?

Measure the ISC coil resistance. That's the most likely thing to damage the ECU without help from misconnected wiring or other user assisted carnage.

 

[1990whitetsiawd]

Yes 11v on both pins in the clips. That was with a battery charger on the car set at start setting which puts the volts at about 13 or 14 on my safc. I have not checked the resistance yet as I just got back from a little christmas shopping. So I will check the isc resistance and the resistance at the injector clips in a little bit.

 

[steve]

11v seems low but that may just be an artifact if your reading 13 to 14v on the SAFC.

Are you measuring with the connector attached to the injector?
The resistance measurement would be across the injector with the connector off, not across the injector clip. If you were measuring with the connector on above then seeing 11v on both pins already verifies that the injector coil isn't open.

 

[1990whitetsiawd]

Sorry guys bad thing on my part here. After it was running on two cylinders months ago I figured oh shoot clean up the engine bay a little bit well I was just thinking about when I was doing that and the fact that I kept getting a Tps code on my car when I would try and start and low and behold I switch the harnesses when I was moving stuff around. So I guess I plugged the TPS sensor harness in the fuel injector resistor box and vice versa. So it runs now but on two cylinders which I am sure will be solved when I get my new PT. Thanks for the help but I guess I should have double checked everything. Sorry for the trouble.

 

[1990whitetsiawd]

New power transistor arrived today car still only runs on two cylinders. So far I have replaced the power transistor,coil pack,swapped cas with a different one. It's just not getting spark to one and four. I am not sure what I should check next.

 

[GRAVEDIGGER]

Sounds to me like you have lost a coil driver in the ECU. You need to check the wire coming from your ECU that goes to your power transistor. There should be one trigger wire for each coil. I'm not sure of the exact pin locations off the top of my head, but all you need to do is find out if you are getting an on/off signal from the computer. You should get a constant voltage reading with the key on and then when you crank you should see the voltage jump around or pulse. If one of your coil drivers is bad you will just get a steady reading while cranking. Since you still are getting spark from one coil you should be able to see what voltage is supposed to look like on that wire while cranking. Even with a bad driver you will be able to see the same voltage as a good driver with key on only.

 

[Twinky-Ninja]

This EXACT thing happened to me.. In my case, the triangular coilpack connector was bad. To test this, start the car (it should run rough if it's still on 2 cyls..) then play around with the coil pack connector (push it togeather, give it a little pull, wiggle it..etc) if it is this connector, you will hear a difference when the plug makes proper contact. Also, unplug the connector (make sure the car is off) and take a look at the pins on both ends, make sure they are not bent or pushed in.
Another symptom i had with this problem was the tach was off in the upper rpm range. I knew i was up around 5k or 6k and the tach was showing 3k or so..
You problem sounds very similar to mine, hopefully it helps.

dave

 

[1990whitetsiawd]

So I tried wiggling the plug for the coils around and that didn't help at all. But now I am getting a code 44 which is for the coil pack or transistor both of which I have replaced with new parts within the last month. I also switched the plug wires on the coil so maybe it would run on the opposite two that it is now and it won't start with them switched. Sometimes it will backfire other times it will just crank real fast and then it will slow way down like it binds up on something. This is only when I switched the wires to.

 

[1990whitetsiawd]

Pulled the computer out again and I think it might be a leaking cap. It looks kinda like a brownish sap looking substance underneath of it. Also by the cap thats closer to the middle has like a perfectly round black circle underneath of it I'm not sure if this is normal or not.

 

[dsmfreak20]

time to throw that eprom in. that ecu is toast.

 

[steve]

I'm not sure if this is normal or not.

Sadly it's normal but not how it should be. The ECU needs some attention and a new set of capacitors and the very minimum.