Missing on 2 Cylinders

[talontsiwinter]

I have a 92 talon TSI AWD. 8000 km on a full rebuild and it starts running on cylinders 1 and 4. i have switched the coils and it still does the same thing. There is fuel but no spark at all on 2 and 3. Could it be the square ignition box on the side of the intake or is it more likely the computer?? i dont wanna buy a 200$ ignition box if its not the problem. Any input would be helpful!
thanks

 

[river]

have you replaced just your plugs and wires yet?

 

[huafist]

I'd try plugs and wires first. If that doesn't do it, I'd swap out the coil, then the ignition pack.

 

[talontsiwinter]

i have new plugs and the wires have less then 1000 k on them
i changed the wires with ones i had and it was the same
i switched the coils and it stayed the same so both coils are fine
must be the ignition box?

 

[steve]

The Power Transistor Module could be bad as could the wires/connectors between the PTM and the coil or from the ECU to the PTM. If you have access to a scope you could check that the ECU is pulling pins 54 and 55 low when it wants to charge and fire the coils. That the signal reaches PTM pins 7 and 2 and that the PTM pulls coil pins 2 and 1 low to match.

Steve

 

[talontsiwinter]

thanks steve,
ill try checking that out, i know its not bad wires between the ecu and the transistor because i have run a jumper wire to check already
but ill see if any power is even coming out of the ECU
ill post again when i have the results.
thanks again
alex

 

[sta500]

MY BUDDIES 2.0 N/A CAR HAD THE SAME PROBLEM IT WOULD ONLY RUN ON TWO CYLINDES, WE SWITCHED THE COIL PACKS AROUND AND ALSO TRIED DIFFERENT COIL PACKS. NONE OF THESE WORKED. FINALLY WE FOUND THAT THE POWER TRANSISTOR, (ONE OF THE TWO PLUGS BELOW THE COIL PACK WAS THE PROBLEM, IT IS A DEAD END NO WIRES COME OUT OF IT, BLACK PLASTIC PIECE BOLTED TO INTAKE ) WAS THE PROBLEM. IT IS THE LONGER PLUG IT SITS VERTICAL IF YOU HAVE A MANUAL LOOK UNDER COIL PACK TESTS AND IT SHOULD SHOW YOU A PIC.

 

[sta500]

I DIDN'T SEE THAT YOU ALREADY KNOW WHAT IM TALKING ABOUT BUT THAT IS PROBALY YOUR PROBLEM, THE IGNITION BOX ON THE INTAKE(POWER TRANSISTOR)

 

[DevilSperm]

why are you yelling?

 

[huafist]

For the love of God, turn off the CAPS LOCK!

And yeah, I'd say the PTM is the problem if all else fails.

 

[gregmondro]

another vote for the ptm, also, sometimes it throws a code for the coils ifi'm not mistaken.

 

[blackdsm97gsx]

I have the same two missing cylinders. I was wondering if that guy ever figured out what it was. It happend to me driving down the freeway and i've done new plugs, wires, and ignition coil. Has anyone had this problem and fixed it?

 

[talontsiwinter]

i havent figured it out yet, in away at school during the week so i wont know untill this week
ill post when i know what the problem is, i ordered the ignition box today.

 

[sta500]

sorry about the caps my computer at work only types in caps the key board is f'd up ordered a new one hasn't come in yet

 

[Project Draven]

yea my 91 lazer rs n/t is running on cylinders 1 and 4 i am gonna try to replace the coil packs tomorrow

 

[InterceptorF]

Hello, I have the same issue on my 95 eclipse GST. I have been trying to get this car running for over two months now. I was able to FORCE it to start with starting fluid and it ran somewhat normal ( all 4 firing) but never started easily. Now after finding the timing off and resetting that and getting the new belt properly tightened ( what a hassle that was) , I have since pulled the plugs and have found that only two spark plugs are firing. I went to the junkyard and found a '91 eclipse and pulled the transistor which had the same part number as the one on the car, and the coils which are not exactly the same shape but it did verify only one coil was firing... so basically no change with the new parts.

I am a newbie to this engine and am trying to make sure I understand all these acronyms... whats a PTM>? in the Haynes manual they call what I believe to be the ECU a PCM... is that correct? If the PTM can cause this issue where is it / what does it look like?

My PCM/ECU has a part number of MD309947. Do I have to use that exact part number if I replace it? is it even the correct one for my GST ?

 

[steve]

I am a newbie to this engine and am trying to make sure I understand all these acronyms... whats a PTM>? in the Haynes manual they call what I believe to be the ECU a PCM... is that correct? If the PTM can cause this issue where is it / what does it look like?

My PCM/ECU has a part number of MD309947. Do I have to use that exact part number if I replace it? is it even the correct one for my GST ?

Get the real manuals. http://www.dsmtuners.com/forums/fre...stions/324090-download-2g-service-manual.html You'll still be missing some of the 95 specific information but you'll have better data than the Haynes book.

PTM = Power Transistor Module. Other cars call it an ignitor but it's the set of transistors used to activate the coils but pulling one side to ground and causing current to flow through the coil. When the transistor turns off the coil fires.

ECU = Engine Computer Unit. On other cars it's called a powertrain computer.

You can used either the MD309947 or MD312464 but 2G turbo ECUs don't go bad that often, at least not without help from the owner or ISC. You may want to have it checked and repaired as needed ratehr than getting a replacement. There is a change that you have one of the EPROM versions of the ECU and it's worth repairing if so.

On 2G's there are a few unexpected parts that can cause it to only fire two cylinders in addition to the expected coil, PTM, or ECU. The two rotational sensors, crank and cam angle can cause a problem since the ECU doesn't know which cylinders to fire when it doesn't know exactly what the crankshaft position is.

Was the car running correctly before all these problems?

 

[Jpierre655]

i had the sam problem when i bought my car. check the cam sensor. it can cause only two cylinders to fire.

do you have any codes?

im not sure exactly how it work but i know our cars have a "waste fire ign system". there is only two signals to the coil pack. one for each of the two coils. my cam sensor was only telling the computer to fire only one coil.

correct me if im wrong but it something like that.

 

[InterceptorF]

yes - before the rebuilt engine was put in it ran fine.. then the kid ran it out of oil and fried it - new crank, pistons, rings, bearings, balancer shaft eliminator kit, valves, timing belt, oil pump, cam sensor, gaskets, clutch, flywheel, spark plugs, spark plug wires, water pump....
The EGR is now blocked off and all the emission hosing disconnected...
I put a new cam sensor in it when I rebuilt the engine

No codes -- I am not sure if it is ODB1 or 2... Kinda hard to get it somewhere to read but the check engine light is on...

 

[steve]

It's OBD II, or at least what passed for OBD II in 95, by nature of the 2G ECU your running.

The answer to my question is really no, it's never run correctly. Doesn't matter what it did before it died, you've never had it run right.

 

[InterceptorF]

OK great to know its ODB II - thanks

and correct - its never ran right since this rebuild has been put back in the car. I have coaxed it into running occasionally but it would either not idle, or act like a demon-child... on all four cylinders for that matter.
I found a pin-out for the EMU on VFAQ but not sure what the signal should look like with an Oscope or how to proceed that direction or I would check it out...

 

[steve]

The 2G manual has signal waveforms for testing.

 

[crazyquik22023]

i would prob say its a good 95% chance that its the power transistor. if not than try to borrow someones ecu and hook that up and see if it works

 

[InterceptorF]

I have looked at the ECU and it looks like I could have a socket put on the board for IC3 ( that looks like the brains of the card). If that were true, Then could I have different EPROMS with different curves for the street and for the track... ?

Where do I have the ECU tested at? I dont think there is a service center / Mitsubishi dealer in Colorado Springs

 

[InterceptorF]

OK - Had the code read - it said the cam sensor circuit was bad - I replaced it and it fixed it. Now it starts and runs strong. thanks to you all and Mike Y for coming by with a OBD II reader... please remember - I replaced that cam sensor during the rebuild process - guess I got a dud om the first one
Thanks again