Started sputtering and missing while driving sixty mph on the freeway

Tiny
SHANE SABENS
  • MEMBER
  • 1992 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
I was driving home and my vehicle started sputtering on the freeway. I was able to still do sixty mph, but got off and checked the cap, rotor, wires, etc. Start vehicle it was fine. I get back on freeway and bam doing the same thing. So far I have replaced cap, rotor and coil. Re-gapped plugs, cleaned throttle body, IAC, TPS and checked fuel pressure and it is thirty one psi. Still same intermittent problem. Please help. I am leaning towards pickup coil in distributor.
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Wednesday, December 21st, 2016 AT 3:05 PM

4 Replies

Tiny
HMAC300
  • EXPERT
Scan for codes and see if any are listed. Fuel pressure should be thirty one at idle with vacuum without it should jump to thirty nine. See if it does that. Check coil wire leading to distributor it should be 5000 ohms per foot and move wire when checking may be breaking down then check resistance of coil see picture. Finally get a spray bottle and spray around coil and wires see if they are leaking. Better after dark.
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Wednesday, December 21st, 2016 AT 3:19 PM
Tiny
CARADIODOC
  • EXPERT
Hold on. We need to actually diagnose this. The pickup coil in the distributor will not cause what you described. The engine will not run at all when that fails. Sputtering that starts suddenly is not going to be solved by regapping the spark plugs. We change them; we do not try to fix old plugs. Our customers would not appreciate spending their money to have us make old parts limp along a little while. Also, forget cleaning the throttle blade. That causes a hesitation on acceleration on GM cars. That comes on over a period of years, never instantly.

The IAC is the "idle air control" motor, also called the automatic idle speed, (AIS) motor. It is involved with what its name implies, idle speed. If you have a problem of low idle speed, check the air passage that valve sits in for carbon blocking it. That has not been a problem for many years with the better additives in today's fuels. The throttle position sensor is the least important sensor for proper engine performance, and it will not cause sputtering or misfires. It is sealed too, so there is nothing related to it you can clean.

The most common cause of this symptom is spark plugs and wires, so start with those.
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Wednesday, December 21st, 2016 AT 3:26 PM
Tiny
SHANE SABENS
  • MEMBER
Changed plugs and wires, still the same.. I'm changing distributor next? Feel like I'm spinning my wheels!
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Thursday, December 22nd, 2016 AT 9:24 PM
Tiny
KEN
  • ADMIN
Hey SHANE,

Because this car is not OBD2 it can be a little hit and miss to try and find the problem. These cars did have a problem with the map sensor which would cause the system to run lean at highers speeds, here is a guide that you can follow to try and get any codes out of it.

https://www.2carpros.com/articles/jeep-diagnostic-trouble-codes-for-car-built-on-or-before-1995-odb1

Please let us know happens so it will help others.

Best, Ken
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Tuesday, December 27th, 2016 AT 8:33 AM

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