when you say icm are you referring to the power transistor or coil?

think hes saying transistor which is the icm



heat can kill them, did you use the thermal grease on the heat sink when you put the last one in?

I didn't use the grease on it the first time honestly but yes I meant the power transistor. Could it really just be the grease that could solve my problem?

I replaced the connector and the unit. Mine went out 2 years ago and no problem yet.

Was the replacement a used one? If so ya gotta remember all these parts roughly the same age and have wear and tear on them. Someone correct me if im wrong, i believe the ecu sends signal to the transistor, so there would have to be a bad/high voltage problem in the ecu to fry the transistor if in fact thats the case.

That's a nasty short that could be causing that. If you have a meter check for any resistance.

Ya, smear some "Arctic Silver" on the backside of that module before remounting it to the mounting plate. This stuff is great heat sink material that is used on CPU computer processors to rid of heat.

These things have quite a bit of current running through the two switcher transistors.

ECU is sending the 12v to the two transistors - both negative and positive voltage - from the signals it receives from the CPS.

What usually happens is that one transistor shorts across allowing the primary coil of one side to remain on all the time preventing the current collapse so the secondary coil can create the high voltage to ignite the two plugs assigned to that one coil. Thus, with that one side remaining on, it can take out the primary side of the coil, making the need of replacement of the entire coil assembly.

Trust me, been there and done that this last winter when my module shorted one side causing my coil to burn out also. $135 bucks from Rock Auto for replacement parts to get my Laser back on the road.

-DSM

The power transistor (ICM) MUST be bolted onto a surface to sink heat transfer to AND that surface MUST be connected to ground. Normally that surface is the head.

Yupp got it from pick and pull. It was 2 years ago and haven't had a problem and its a daily 5.0 puller.

Hey guys, I have an occasional cylinder 3 misfire (0303) which occurs when the car is around 1000-2500 rpm. The check engine light comes on and I lose 1 or maybe 2 cylinders. I clear the code and turn the car off and on again - the cylinders come back. Power is great and if I run at high RPMs, this doesn't occur. I changed the coils and the spark-plugs. Swapped the wires for cyl4 with cyl3 to see if its the wire for #3, but the cel is still for cylinder 3, so it's not the wire. Running out of ideas, so could it be the power transistor? If it is, why would it only fail cylinder 3? I should say that when this first happened, I opened the spark-plugs cover and found oil in the plug tubes of cyl2 and 3. I changed the valve cover gasket/seals and cleaned it up good, changed the plugs and later the coils as I said. I thought this would fix it, but there is something else....

Could be your injector relays in ecu causing intermitten problems but if it was transistor it would just go out and be out. But you didn't say you changed wires. You might want to change spark plug wires. Taylor's are some good wires.

I did swap the wires between cylinders 3 and 4, but the misfire was still on cylinder 3, so I ruled out the wires. Are you saying that there are injector relays inside the ecu? I know that there are caps in the ecu that can go bad, is this what you are referring to? I think the ecu could be the problem because after I get the misfire and lose a cylinder, all I have to do is turn the car off, then turn it on again and the misfire is gone. It's like the ecu is resetting and the problem is fixed until the next time. I am going to listen to the injectors during a misfire condition to see if #3 is out when it happens. I did pull out the wire for cylinder 3 during misfire condition and it was sparking on the engine. So unless the spark is not strong enough or it's not sparking at the correct time, it would have to be fuel not getting in the cylinder. Could the ecu just disable an injector when it detects misfire? Or may be misfire is detected because the injector stops?

tgounev said:

I did swap the wires between cylinders 3 and 4, but the misfire was still on cylinder 3, so I ruled out the wires. Are you saying that there are injector relays inside the ecu? I know that there are caps in the ecu that can go bad, is this what you are referring to? I think the ecu could be the problem because after I get the misfire and lose a cylinder, all I have to do is turn the car off, then turn it on again and the misfire is gone. It's like the ecu is resetting and the problem is fixed until the next time. I am going to listen to the injectors during a misfire condition to see if #3 is out when it happens. I did pull out the wire for cylinder 3 during misfire condition and it was sparking on the engine. So unless the spark is not strong enough or it's not sparking at the correct time, it would have to be fuel not getting in the cylinder. Could the ecu just disable an injector when it detects misfire? Or may be misfire is detected because the injector stops?

Click to expand...

Are you using a 1G CAS?
Yes, the ECU will disable an injector when it detects misfire. Turning the key off will reset the ECU until it completes another 300 second highway cruise.
More info:
http://www.dsmtuners.com/threads/po300-code-like-clockwork.481913/#post-153445000

Jim

Thanks Jim. No, I am not using 1g cas. Everything is 2g. In the link you quoted, it was suggested to disable the misfire detection in DSMLink. The only place I found in my DSMLink v2 was a check mark on Misfire Detection under DTCs. So I guess you just uncheck it? Any negatives in doing this? After all, I don't know the underlying reason for the misfire.

Have you done a compression test? How this system works is through the lowest resistance 2 and 3 work off the same coil so when the cas sends a signal it you have fuel in cylinder 3 that would have the least resistance so it fires but if you have low compression in that cylinder it won't fire aka a miss. So if you don't want to do a compression test pull the plug off the injector and see if things change also check to see if the pins are not curroded or to big of a gap. But yes you have injector relays inside the ecu that could go bad.

I will check compression when I get some free time. Meanwhile I replaced the Power transistor, but no improvement. So up to this point, new plugs, new coils, new power transistor and swapping wires don’t fix the problem (still 0303 code). I have been running E85 setup with 1150cc injectors for several years now. Sometimes I switch to pump gas in the very cold moths. I had switched to pump gas when the misfire occurred, so last night I went to the gas station to fill up with E85 and see if that changes anything. I filled up and adjusted my global fuel setting to zero the LTFTs. Then drove back home on the highway. Good power, and as I stepped on it, my WB fuel gauge went down toward 10:1 as expected, but as the turbo kicked in hard and the RPMs went higher, the WB started creeping toward 11, 12, and even hit 13:1. I never run my car that lean. This is a stable DSMLink configuration that I have been running for years, and I’ve never had my WB go leaner than 11:1 ratio under WOT for safety purposes. I did this a few more times and the same thing happened. Once I got to the secondary streets running ~2500RPM, the misfire occurred as before. Got home and let it idle in the garage for a minute. The WB got pegged at 18:1 and the O2 got pegged at 0.02 Volts. The idle crept up to 1100 rpm. ? The LTFTs did not move much. They should’ve gone to their max (I think +15%). It’s like the car got supper lean, but the ECU didn’t or couldn’t correct for it. Is the ECU wacked and it’s not giving the injectors the correct info, is the fuel pressure too low – I am lost.

Maybe you've got a dirty injector have you thought about cleaning them or sending them off to get cleaned?[DOUBLEPOST=1415132700][/DOUBLEPOST]Wait was the car still cold when you start to get on it?

No, the car was warm. I will pull the ECU out (over the weekend) to see if there are obvious problems. It's 19 years old, so who knows. I'll probably send it to ECMTuning to get it fixed up. I could swap injectors 3 and 4 to see if the DTC code goes to cylinder 4. Could my fuel pump (Walbro 255) be going bad gradually? I don't have a fuel pressure gauge.

That's a good move switch them and let us know what happens.

I went ahead and swapped injectors 3 and 4, and guess what - the DTC changed to "cylinder 4 misfire"! So injector 3 is bad. They are FIC 1150cc. I am thinking of sending all four of them to FIC for cleaning (it says $20 per injector). Any other suggestions? I don't know how to clean or test injectors.

If you can find a justice brother distributor get a bottle of fuel injection cleaner and run it in your tank or some BG injection cleaner. You could also get a fuel hose the same diameter of the injector and fill the hose up with injection cleaner. Use a hose clamp on the injector fill it up then hook it up to a air hose and pressurize just a little and use a 9volt batter and pulsate the injector into a bucket. But be very cautious. There are videos on youtube to properly do it but I would try just the bottle in the tank first Justice bros over BG.

You can try the the tank cleaner first but know that it rarely works once they are already clogged that bad. DIY Injector cleaning: http://www.dsmtuners.com/threads/cold-weather-engine-issues.448803/#post-153136134

I sent the injectors to FIC for cleaning today. I'll report the results when I get them back. Thanks guys!

Your post is what made me think of DIY thanks.