Hi guys,

Haven't checked on here for a while, changed alot!

I've got an issue that started about a month ago. I'll give you details, any advice would be great.

1996, 1.8T Sport, AEB, Manual. Chipped but still with K03, otherwise stock. Car has done 185k now, but I have replaced oil pump, head gasket, water pump and turbo about 2 years ago.

Car has developed a heavy misfire under load, pretty much inline with the start of boost, but only really under load.

If you lightly build the boost and feather the throttle it will still reach higher RPMs without missing.

I suspected MAF, swapped and it still does it. Checked for codes, none present except for unreadable signal from TPS, but cleared and drove again, rechecked and no codes.

Would the N75 cause something like this? Without throwing up a code? Or am I to begin looking at coil packs?

It's making the car useless to drive, usually it runs very well and is still doing great for the daily run to work.

Any help or pointers to old threads would be really appreciated.

Thanks,
Paul

 

My guess would be the diverter valve, N75. I believe reduced boost
wouldn't throw a CEL.

 

plugs are either dying or the gap has grown causing the misfires. Best to just spend $10 and get new plugs and gap them down to .028

 

also check all vaccume/intercooler lines. that sounds exactly like what happened when i used to pop my intercooler pipes off from too much boost. im not sure about the quality of the plumbing/clamps on the stock IC, but i wouldnt be suprised that at 180k there is a crack or disconnected pipe somewhere.

also try what cincy said.

w/ no CEL its not very likely that its a coilpack esp. if this has been happening for a while.

 

if its not the plugs, its most likely the coils!

 

Thanks, I'll try swapping the plugs and check for vacumn leaks tomorrow. I would have been suprised at coil packs as most of the issues I've seen seem to be with the later engines.

The lack of CEL and code was the annoying thing!

 

a coil pack or a blown ICM would show a flashing CEL. infact any misfires show a flashing CEL even if you just miss one time on one cylinder, youll have a flashing CEL for 50 miles i think.

i wouldnt start buyinig coilpacks at $80 a pop, or a new ICM which is $180, until your sure thats the problem, and even w/o seeing/hearing the car in person i can almost bet its not that. unless you have a major problem w/ the ECU that its not showing CEL's. but ive never heard of that...ever.

 

how much boost would it take to pop the intercooler hoses if they were connected correctly? seems like it would take quite a bit of pressure. just curious.

 

The clamps can and most likely will come loose over time due to the pipes shaking. Add that in with getting oil into the system from the breather system, it doesnt take much to blow them off.

 

You get the prize Cincy, plug gaps had opened up to 42 thou. Re gapped and it's running 100% better again!

I'll pick up a new set this week.

Any advice on replacements? I'm running NGK 7E's at the moment.