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Need Help to Diagnose: Stumble and Occasional backfire

  • Thread starter Thread starter 94-302-vert
  • Start date Start date Aug 17, 2011

94-302-vert

Active Member
Aug 16, 2004
1,947
2
36
NE CT
Aug 17, 2011
#1
  • Aug 17, 2011
  • #1
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

Recently finished repairing my rear
20+ Year Stangneter
Aug 26, 2004
2,373
140
113
Foothill Ranch, CA
Aug 17, 2011
#2
  • Aug 17, 2011
  • #2
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

15 Year Member
Oct 3, 2003
5,589
9
98
Bethesda, MD
Aug 17, 2011
#3
  • Aug 17, 2011
  • #3
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

Active Member
Aug 16, 2004
1,947
2
36
NE CT
Aug 17, 2011
#4
  • Aug 17, 2011
  • #4
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

15 Year Member
Oct 3, 2003
5,589
9
98
Bethesda, MD
Aug 17, 2011
#5
  • Aug 17, 2011
  • #5
94-302-vert said:
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 ???
Click to expand...

yeah, sounds like time to do a compression test.
 
S

screamin5oh

Member
Jul 13, 2011
170
5
19
centerville oh
Aug 18, 2011
#6
  • Aug 18, 2011
  • #6
yea could be getting alot of blow by now
 

alleymad95GT

Member
Jul 14, 2009
204
0
16
Okemos, Michigan
Aug 19, 2011
#7
  • Aug 19, 2011
  • #7
Doesn't the dipstick normally pop out due to excessive crankcase pressure? Just curious...
 

94-302-vert

Active Member
Aug 16, 2004
1,947
2
36
NE CT
Aug 19, 2011
#8
  • Aug 19, 2011
  • #8
So noone is thinking of a sensor or component that can cause these issues???
 

PUNISHER RACING

Active Member
Aug 27, 2007
1,124
0
36
FORD CITY, PA.
Aug 19, 2011
#9
  • Aug 19, 2011
  • #9
might be gettn some slop in the chain as well and ur timing is not gonna be accurate
 
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