strange cutting out/bogging/backfiring problem

[essfourteen]

i have a 95 ka-t with a blow through mafs that has been running amazingly since last june up until recently. this is what happened

yesterday on a trip from tallahassee to daytona, florida which is a ~250 mile, 4 hour trip, i started having and overheating problem. the characteristics were a blown headgasket. it started heating up after 100 miles of travel, i stopped, let it cool down, and kept driving where it did it 40 mile later, then 20 miles again after that then just bobbed kind of for the rest of the trip. so the next day i did a compression test and it came out fine. all cylinders were 180 or over. so i changed the thermostat and the old one had seemed somewhat stuck closed. i also changed my oil and washed the engine bay.

the washing of the engine bay is what my dad and i think the problem is. we left the house and made a 15 or so mile trip where the temps stayed normal but a new problem arrived. whenever you would start to head toward boost, the entire engine would buck, stutter/hesitate, and backfire. we thought water had gotten into the spark plugs so when we got home we dried out every spark plug and harness clip in the engine bay, and i checked for any boost leaks. well its been an entire day and we have been trying it out at intervals all day and its still doing it. it seems to be getting better, but its stil pretty bad. if anyone can halep that would be awsome.

thanks, dimitri

[Logan76]

Check your MAF, also Check your distributor and make sure your timing is good. When my car ran like that it was a MAF sensor problem, but you could be out of time, or it could be a fuel issue. You said you checked for boost leaks. You just have to check everything until you find your problem, I probably didnt help you, but I tried.

[Zippy69]

Sounds like a leak in the i/c piping.

[Florida240sx]

What is spark plug gap? Chance one of them closed up? Check all connections, Run your ecu yet to see if it is throwing any codes?

[WDRacing]

Examine the plug wires themselves. I cooked one and ran into a bad stutter when under WOT.

WD

[essfourteen]

thanks guys, ill go check these things out. the spark plug thing could be plausible because i too them out to do the compression test.

[essfourteen]

i found out the bucking problem. i guess i didnt look hard enough for the boost leak, but i found it.

its still over heating though. it doesnt overheat until it start to get on it though. thats the only time it seems to do it. but after that when im not getting on it anymore it wont stay back at normal, it bobs up and down and never stays at a normal temp.

[spooled240]

still overheating with the old thermo? <this is the stock one right? I think this is the problem, only other possibilities would be low coolant level or a clogged radiator which I doubt.

[essfourteen]

i found out the bucking problem. i guess i didnt look hard enough for the boost leak, but i found it.

its still over heating though. it doesnt overheat until it start to get on it though. thats the only time it seems to do it. but after that when im not getting on it anymore it wont stay back at normal, it bobs up and down and never stays at a normal temp.

[essfourteen]

so its still bucking, but not while the wastgate arm is disconnected so there must be some boost leak im missing or maybe a bad injector o-ring or something.

but no, its not the old thermo, its a new one. the system is completely burped. i did a comression test and it was slowly losing compression. i am closing off certain things like my heater core and turbo coolant lines individually to mark off possible leak spots. i think it might be the radiator, mainly because over winter break i had to seal it up with wet-weld. im going to try another radiator after i check the other stuff to see if thats it.