Question about 1998 Jeep Cherokee

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1998 Jeep XJ, has no injector pulse. How do you diagnose if it is a PCM fault, or something else not allowing the PCM to do its job?

The following has been confirmed; Yes there is spark, yes there is 10.5V at the injector when cranking, yes there is 49psi fuel pressure when cranking, yes there are pulse voltage at the Cam and Crank sensors. No there are no codes or check engine light

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6 Suggested Answers

6ya6ya

6ya staff

  • 2 Answers

SOURCE:

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Posted on Jan 02, 2017

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Anonymous

  • 108 Answers

SOURCE: no spark at coil

check ignition pick-up coil and ignition module

Posted on Mar 31, 2009

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Anonymous

  • 2 Answers

SOURCE: 1996 Jeep Grand Cherokee No Start

I would be thinking that there is a good chance that you need to be checking out replacing the computer, if you aren't getting any communication with the proper scan tool then the computer isn't communicating with anything in the vehicle...... I would have guessed first off that the ignition control module might be bad but that is obviously part of the computer also, I would be looking in that direction.

Posted on Sep 19, 2009

Gil Nolasco

  • 306 Answers

SOURCE: jeep grand cherokee

Just trying to help. Jeep dealer won't tell you what code means? My guess would be in the intake system. MAF sensor? Air intake leak? I don't think its the pos. sensors because your engine would not run (been there done that). Your throttle is cable driven?

Posted on Mar 05, 2010

witmoz

Robert Monigold

  • 390 Answers

SOURCE: Need a complete wiring diagram '90 jeep laredo 4.0

you can get a hanes book at any autoparts store.But you may want to check the tps also.

Posted on Jun 12, 2010

Nicolo Carlo Parazo

  • 2187 Answers

SOURCE: 2002 WG Jeep Grand Cherokee

The error P1130 and P1131 is for the fuel trim and lean fuel mixture respectively. This tells me that this may be an issue with the air fuel mixture or its reached its limits in compensating for the incorrect mixture. You could try to clean out the intake first using carb cleaner spray or tuner spray to clean out the intake and the MAF sensor which measures the air that comes in. Check also if there are leaks or gaps on the air duct found between the air filter and the intake manifold and the intake plenum. Leaks would cause the system to get an incorrect reading. If it were a faulty sensor you should get the error code for the sensor and you may have issues starting the engine up.

Check also the vacuum hoses which may be loose or cracked that needs replacing or refitting. This is also a common cause. I also do not rule out the possibility of the fuel sensors going or starting to go bad. The PCV may also need cleaning or replacing.

With all mentioned items go check first the leaks of the intake system and the vacuum lines as these are found to be common. Some leaks or cracks are minimal but is crucial to the sensors.

Posted on Jun 22, 2011

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3 Answers

2004 Grand Cherokee (4.0)intermittent #1 cyl misfire and #1 injector control circuit fault (3 wks). Problem began after changing spark plugs. Replaced: coil pack, 6 injectors, & Bank #1-#2 O2 sensors.


I worked on one with the same issue. Ended up being the harness burned at the rear of the engine on the exhaust. Burned wires going to coil pack and shorted when I moved the wires to the coil packs.

Feb 22, 2017 | Jeep Cars & Trucks

1 Answer

How to remove a dashboard from a 1994 grand cherokee


XJ 94
its not bad, wana bet? 90% are not.
(i used to fix them)
so the PCM,. the FSM book covers that.
why not read that.
JEEPJX
PCM is baD ONLY WHEN inputs good, and its outputs are bad.
(and outputs not shorted) !!!
(same or all computers on earth)
lose of power to PCM or ground
or bad power.(weak, or intermittent)


Got DTC errors , post them?
innova 3140 best bank for buck on 93-95 jeeps. !!!
that is a low priced scan tool

are you having ASD relay issues?
http://www.fixkick.com/Jeeps/ASD.html


see XJ 95 here (same i think)
http://colorado4wheel.com/manuals/Jeep/XJ/

page 8D-23
engine bay next to Air cleaner.

to diagnose any car, a real scan tool is best.
or you will need a full lab of meters and scopes. like me.
the scan tool show up things the keyon/off trick does not.
http://www.fixkick.com/Jeeps/jeeps.html#poor_mans-scan


25499888-tk5pw0guzkbs2wb12fwiwrb2-5-0.jpg

Mar 01, 2015 | 1994 Jeep Grand Cherokee

1 Answer

Jaguar xj sport 3.2 no spark or injector pulse


If ECU has crank signal and engine turns over, ECU should give injectors a pulse and trigger the ignition. If not ECU might be bad. You should check power and grounds going to ECU. There are usually multiple power and grounds going into ECU

If you need further help, reach me via phone at https://www.6ya.com/expert/david_f2436a37cbb50365

Jan 06, 2014 | Cars & Trucks

1 Answer

2004 jeep grand Cherokee fuel injectors stay open


If not pulsing, could be a bad pcm. The computer grounds the injectors internally for a split second to pulse them . If trash or debris is not making them stick open, buy a "noid light" for checking injector circuits. Plug it in to #1 or #5 and crank engine over: if circuit is working right, noid light will be blinking. If light is on steady, computer is not interrupting ground to cause pulsing.

Jul 11, 2013 | Jeep Grand Cherokee Cars & Trucks

1 Answer

Pcm is not grounding injectors. need a pin diagram and ground location diagram


Ground points are in different locations throughout wiring harness. If you had any work done to engine it is very possible to have missed one of the grounding eyelets during the process of putting things together. Check along wiring harness in any area you can see or reach to try to locate any loose or disconnected ground looks.

Nov 23, 2011 | 1998 Pontiac Bonneville

1 Answer

No power to the injectors



No injector pulse at injectors:
a) check fuses
b) use scan tool to read RPM at PCM while cranking. Ask question specifying RPM PID data.
c) crank sensor/cam sensor/ign. module/wiring fault
d) stuff not plugged in properly
4) check fuses
5) dead PCM note PCM pulses injector ground based on sensor input, power is constant from ignition
how are you testing injectors theres something called a noid light auto parts store let you use them free you have to test it on the injector itself what did you car do before it died does it turn over but not start

Dec 03, 2010 | 2002 Pontiac Grand Am

1 Answer

2004 Jeep G Cherokee diagnostic code open injector


It could be a faulty pcm or wiring as you stated in you post. the pcm pulses a ground to the injector circuit allowing the solenoid in the injector to activate momentarily are inject fuel into the intake. if you give me the engine size. V8 4.7L or strait 6 cylinder 4.0L and i will post the proper wiring diagram for the fuel injectors to help you out with your battle

Jan 09, 2009 | 2004 Jeep Grand Cherokee

1 Answer

2000 jeep wrangler no injector pulse


Have you tested the PCM fuse??

Sep 10, 2008 | 2000 Jeep Wrangler

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