Need Help to Diagnose: Stumble and Occasional backfire

[94-302-vert]

Haven't been here in a while. My car is a 94 with 225k miles on it. The longblock, injectors, throttle body, wiring, distributor, and most sensors are all stock.

The coil has about 100k miles on it.

About 2 months ago the car noticably lost power at the top end and started hesitating when going from cruisng to accelerating. This started to get worse so I changed plugs/wires/cap/rotor. This made a slight difference.

The problem continued to get worse and I developed an exhaust leak (header to x-pipe). I fixed the exhaust leak, treated the gas with fuesl system cleaner a couple times, changed the fuel filter, and seafoamed the intake. The problem is still there and keeps getting worse.

Last night I pulled the SPOUT and the car stumbled and backfired horribly.

I have a TWEECer RT but I am not proficcinet with it. What can I datalog or watch to try and determine what has failed. I am not sure if it is an injector / distributor (PIP) / ignition module / etc.

Thoughts????

 

[Chythar]

I'm having similar issues, though not quite as bad as what you're describing. My first guess would be the PIP in the distributor starting to fail. You could run a cylinder balance test and see if any one cylinder isn't working well, that may indicate a fuel injector problem.

 

[BlackVert]

you don't have a wideband, do you? if so, a datalog could probably tell you if you are going rich or lean.

might you have made a change to the tune around the time when this started? can you go back to the last tune you had before this behavior started?

 

[94-302-vert]

I did not change the tune since 2008. In fact I reloaded that tune JIC with no benfit.

I just took the timing light out. Without the spout the timing is constant... However the timing mark is on the drivers side of the block.... Connected to cyl #1 plug wire.... I also reved the engine and the timing stayed. Plugged the spout back in and it moved with RPM but settled right back in without issue (dist has not been out in ~60k miles).

I also datalogged for a minute and didn't see anything out of whack one side to the other....

Another odd thing is that the last couple times I have opened the hood the dipstick is out of the tube like 4"... Never had this problem before so not sure if I have a cylinder with bad compression causing blowby or ???

 

[BlackVert]

Another odd thing is that the last couple times I have opened the hood the dipstick is out of the tube like 4"... Never had this problem before so not sure if I have a cylinder with bad compression causing blowby or ???

yeah, sounds like time to do a compression test.

 

[screamin5oh]

yea could be getting alot of blow by now

 

[alleymad95GT]

Doesn't the dipstick normally pop out due to excessive crankcase pressure? Just curious...

 

[94-302-vert]

So noone is thinking of a sensor or component that can cause these issues???

 

[PUNISHER RACING]

might be gettn some slop in the chain as well and ur timing is not gonna be accurate