Help me, engine kills itself, and hesitates really bad

[xns]

I had a shop swap a DOHC into my 89. It was running decent at first... then I replaced the stock intake with an Ingen intake...seemed to run ok... I didn't have any gauges working and my water pump failed and the engine overheated. My compression in #4 went down to 145 from 185:(

The water pump was replaced and now all gauges are working properly... but the car is bareley drivable. It starts hard and idles all over the place It will run really stong for a few seconds but as the RPM climb to 2500+ it cuts out like someone is turning the ignition off and on. It jerks and bucks all over ... sort of the like the first time you ever drove a clutch...

Me and my dad are guessing it has something to do with the MAF and ECU. But we really don't know what to do next. WE are not taking it to the same shop again as those guys have spent many hours trying to figure this out just to look at us and say--- shoulda never swapped out the good running SOHC... Yeah well bite me... So my 240sx Brothers... what is my next move? Any ideas on what is making my car run like crap?

[brisknfade]

When you disconnect the MAF and you rev it, the car usually goes to about 2000 or 2500 RPM then it wont go any higher.

If the computer doesent recieve the info about how much air is going into the engine, then it can't adjust the Air/Fuel mixture properly. So it doesnt let it rev high enough to cause any serious damage.

So that may be your problem. Since you changed the intake and it started doing that there it's probably that. If it is hooked up, maybe the wires or something on it are damaged. The overheating may have contributed to that.

I Disconnected the MAF from my 14 and ran it, did the exact same thing. It keeps on bouncing off of 2200 or something like that.

[eds13]

i'd put the stock intake back on and see if that makes a difference

[574-240sx]

Sounds like MAF. I know mine was not completely plugged it before. If thats not it try cleaning it.

[Arrow]

in addition to what the others have said... Now I'm not sure about the compression and all... but you might have had a slight crack or something with the headgasket on your #4 cylinder.

Definately check your MAF... although something with the wiring might have not been set up properly when the shop did the swap and it just took some time to loosen or fall apart...... I personally don't like to trust shops to do something that they aren't accustomed to do (most performance shops do sr's and not really the DOHC.... at least that I know of)

If I haven't said it before I am by far NOT AN EXPERT and I can be wrong and if I am correct me. This is just my opinion and two cents if you call it .