Terrible shudder/no power. Help!

[doubleclutch]

I have been having an issue and it seems to keep getting worse.

My car tends to seem to drop to three cylinders randomly. It happens in every gear and tends to be at lower rpms. Going to WOT while this is happening doesn't fix anything. At first it was only on the highway now it is hard to drive even around town (no power when it drops to 3). As soon as I let of the gas it goes back to 4. But if i step on the gas again without downshifting or pushing the clutch in and reving a time or two it will go right back to 3. I have tried the following:

- Swap the plugs
- Swap the wires
- Replace coil pack
- Replace Transistor
- Check fuel pump voltage (~11.5)
- Listen to injector operation (all sounded the same)
- BLT (only leak was the TB shaft seals. Decent amount of leak throught he turbo feed lines)
- Remove air filter and try to repeat issue (still happened)
- replace fuel filter (see below)
- Checked knock sensor for goo (no goo)
- Checked timing (dead on)

The only thing that did anything to alleviate the problem was the fuel filter. After the fuel filter i drove for ~4 hours before the symptoms came back. Everything else has been largely no change.

I have a CEL for P0300 and either the fuel limit one I believe for too rich. I did have p0302 until i did the coil pack. Not sure if that matters.

I am at a loss as to what it could be. Only other things I can think of is CAS fuel pump, fpr, or ECU.

I have to assume it is getting air. It pulls good vaccuum at idle (also misfires) and turbo boosts normal ~12psi. Fuel and spark signal are the only things I can think of.

Any ideas? I am at my wits end. I cant just keep replacing parts and hoping.

Also anyone in southeast michigan tht would let my try there ecu or CAS?

 

[1davho]

Sounds like it could be a plugged catalytic converter.

 

[doubleclutch]

Highly unlikely. I have a 3in turbo back with a very small cat. 3 in dia. X 3in long. Installed it about a year ago.

 

[1davho]

Could be a bad mass airflow sensor also. Do you have any way to log sensors?

 

[doubleclutch]

Not really. I looked at the maf yesterday and it looked ok. I know that doesn't count for much. I really need to find someone with a logger or something I can borrow.

 

[black97spyder]

If you were an auto I would say check you flexplate and see if It's broke. That would cause similar symptoms of whats going on with your car... But your not auto.

Id try the cat converter first, as you can buy a cat "test pipe" for like $40 on eBay and It's just a straight pipe that bolts ima place of your cat and would let u know real fast if it a a bad cat converter.... And it adds like 15hp

 

[doubleclutch]

I can check the cat. It is a magnaflow high flow spun cat. 1 year old. The thing hard has any catalyst material in it to plug. But I will look.

Any other ideas?

 

[forcfedtalon]

Check volts/ohms to all injecrors..I had same problem . Sounded like a suby. Checked voltage/ohms on injector imp. And one was way off..rewired with solder and all was well..

 

[doubleclutch]

Do you mean from the ECU to the connector for the ohms or simply the ohms across the injector?

Also how did you check the voltage during impulse? just unplug one and measure then plug back in while running?

I have checked the impedance across the resistors and they are all similar.

 

[SICK SOCIETY DSM90]

I have been reading your problem and your on the right track if you can if its losing that much power do an compression test on all cylinder's you maybe losing a cylinder. In your diagnostics I do not see it listed so let me know if you have already but its a quick test and cheap. sounds like every else is fine your cat would have to be totally blocked or leaking to get a notable hp loss. I just bought a 1g talon that was sitting in a corn field with dust and everything for 6 years and still not clogged so just some input. Sounds like a problem that can be resolved pretty easy

 

[doubleclutch]

SICK, it only loses power when it starts missing. I would assume if a cylinder was going do to a compression related issue it would be more constant than it is.

Noticed that my throttle cable needed a good adjustment. Did that. now i get better response on the pedal and WOT is WOT.

Didn't fix the problem. But i noticed that only while i am running on three. the RPMs act all weird like there is a short in the wire. The tach jumps around the rpm I assume I am at randomly. The car seems to not deviate from the actual rpm. Is this normal because it is running rough? Or is this my CPS or the ECU going bad?

Edit: I did trace the PTU wires back into the harness (actually i believe it is for the injectors, CAS, Map, PTU Etc) and I beleive I found the ground wire for all of those. It looks like there is some corrosion in the connector. Not horrible but could be better. I am going to try cleaning that and the ground that is on the intake that goes to the fire wall. I feel it is sorta a long shot but I am running out of ideas.

 

[doubleclutch]

Checked grounds today, Seemed fine. (less than 0.8 ohms from connectors to battery terminal)

Checked voltage and impendance of injectors. All injectors had the same impedance and were seeing the same voltage (7.05)

I did get the car to act up during a drive and pulled over and it stayed on what I assume is three cylinders for a bit. I was able to pull the injector clip to injectors 2 and 3 while it was like that. Both times it bogged down.

If i get a chance I will pull 1 and 2 and see if it makes a difference.

I almost feel like it isn't missing per say but that it is runnign out of timing. pulling an injector doesn't quite sound like the "subie" sound that it makes when it is freaking out.

 

[1davho]

Make sure your transistor is staying plugged in. I have had one that would come loose and it would intermittently cut out two cylinders.

 

[doubleclutch]

Still hsd the clip when t his all started. Never seems to be loose

 

[1davho]

You have stock injectors and stock ecu, right?

 

[Twinturbo120]

My tach was acting up and the car was running on 2 cylinders. It was the ecu for me, just take it apart and inspect it.

 

[boost198]

Mine was acting like that it was the ecu

 

[doubleclutch]

I was trying to avoid that but I am outta options. If it is bad I am gonna have to convince yhe wife I need dsmlink.

Pulled the ECU. First picture looks like it is bad right? The rest of the board looks ok. What are those little black boxes anyways?

 

[doubleclutch]

Installed the "new" 95 Eprom today. Went for a short drive and no shudder. I will take it to work tomorrow and see what happens.

Also installed a new K&N filter in place of the megan one that was caked with junk.

Two things i noticed:

1) if I rev and then let off, the computer cuts the revs down sharply jumping ~1000 revs in less than a half second. I find this odd. It doesn't really affect drivebility but is something wrong?

2) The fuel maps seem to be different. A little less power at partial throttle in the 2K to 2.5k range and less boost. Anyone else experience that?

I will mark as resolved if I get a couple of drives in with no issues.

 

[Black-Out]

I was trying to avoid that but I am outta options. If it is bad I am gonna have to convince yhe wife I need dsmlink.

Pulled the ECU. First picture looks like it is bad right? The rest of the board looks ok. What are those little black boxes anyways?

Just for the record the little "black boxes" are surface mount Technology diodes just incase you were still wondering .......

 

[2G_LOVER]

Having the same problem on my 98' GSX.
Feels like 1 or 2 cyls drop then I lose a bunch of power, and when I accelerate it feels like its hauling on the engine while getting all of its power from the turbo.

RPMS bouncing all over the place.

 

[doubleclutch]

Try the pt first. Cheaper and from the research I did usually the problem. Mine seemed to be the ecu though so good luck.