Stealth SOHC issues... sporadic...

[Boost4VR4]

I just got my car back from XPAuto and they had done quite a bit of work:

Engine related items:
Fuel filter was replaced
Rear head rebuilt new head gasket on the rear head
2 bad injectors replaced

Here's my issue. When I drove the car at first, it was 88 degress and when I drove it for a bit, the car started to buck when >20% engine load was introduced. I took the car out around 9PM and the car drove perfect for an hour...

I have replaced TPS, IAC, plugs and wires have been changed, distributor rotor is new, cap is new.

I am stumped... Feels like fuel related, but car ran great in the evening... Fuel pump???

[Blackmount]

My SL did same thing. It was the Maf. Try replacing urs

[Boost4VR4]

I was leaning towards that as well. The problem I had though was when I put it in the shop, 2 injectors went bad and it ran on 4 cylinders.... So what is your reasoning behind the MAF?

[Blackmount]

Experience. I had a bad bucking problem few weeks ago. If i was light on throttle it would start to buck or act like it was fuel cutting, the heavier i was on throttle the higher itd do it in the rpms. Replaced maf, fixed issue... vacuum leak could cause.

Usually bad injectors will just cause a miss or make the car feel like a absolute turd. Bucking in my experience has always been the ecu not reading afr properly.. i had same problem on one of my DSMs... the Maf wasnt bad but itd throw code for maf, turned out the problem was in the ecu itself so u can consider that too.

P.S I did NOT have a CEL when my MAF went bad on my SL.

[Boost4VR4]

Hmm... that is a really quick fix too... I will see about a replacement... I drove the car a lot today and it never did any bucking... It is close to 90 today too...

[GTOJOE]

you can tell if it's the MAF by simply unplugging it. The car will run like a dog but it will allow you to see if the bucking/stumbling is gone.

[Boost4VR4]

Car dies when I unplug the MAF.

[GTOJOE]

unplug it before starting the car.

[Boost4VR4]

I drove the car Saturday and Sunday and no issues, no bucking, no stumbling, no hesitation. Car drove great actually.

I was driving the car this morning and the bucking and stumbling didn't happen but if I put some load on the engine and went half throttle as the RPMS would pick up, I could feel a quick stumble in a few areas in the powerband. I am thinking that I have a MAF problem, fuel pump is definitely working. I think the air is being metered incorrectly causing the ECU to lean out and causing the quick stutter. The stutter is so slight it feels like a road bump even when I am flat road. I am going to try the MAF unplug to check it tonight in the meantime I may just pick up a MAF to be safe. I am also going to pick up a set of spark plugs to have with me when I go to NG as well as the MAF.

[GTOJOE]

your handle is boostedvr4 but your talking about a SOHC N/A car aren't we? if you are running a vr-4/tt wiring harness then you would have the fuel pump resistor. If so I highly recommend you bypass it.

Stealth 316 - Fuel Pump Relay/Resistor Bypass