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99' Cherokee Sport I.F.I- 4.0 cranks but will not start


 
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spotter6
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Joined: 16 Nov 2006
Location: Schenectady,NY

PostPosted: Thu Nov 16, 2006 7:22 am    Post subject: 99' Cherokee Sport I.F.I- 4.0 cranks but will not start Reply with quote

Hello, my 99' Cherokee Sport In-line Fuel Injected 4.0 (242ci) approx 80k, is not cooperating with me. The check engine light came on one morning driving into work, engine was cold and so was the weather. I tend to drive it hard as well I love the high output 4.0, lots of get up and go. This had happened to me previously and a friend of mine a Jeep Tech had mentioned it was probably due to a misfire and I needed a tune up he had mentioned 99% of the time a tune up and resetting the computer does the job. Sure enough he was right that was a year ago, so this time I reset the computer again (disconnected the negative wire for 20min). While I was waiting the 20min I decided to spray down the injector bar with carb and choke cleaner since it looked a bit corroded. I sprayed most of the connectors in that area (injectors and throttle body ect), and no where else. I reconnected the battery and started the jeep it idled roughly for about a minute and stalled. It has not started since, it will crank over, but the Amp/Volt gauge and Fuel gauge nolonger work (1/4 tank and fully charged battery) but they read nothing, the oil pressure gage does move slightly though. I have also noticed that the fuel pump is not getting any power. I have checked the relays and fuses and all appear to be fine, I even replaced the ASD and Fuel Pump Relay. All lights and the radio are working..Question::Have I shorted out something near the throttle body by attemtping to clean it and if so why would this shut down my fuel pump? Or is my PCM now fried? I'd contact my friend but he is unavailable and I need to get up and running pronto. If it is the PCM any suggections as to where I can find one? CarQuest said they were not available. P.S. My Haynes manual is proving to be worthless in this situation.
Any help is much appreciated and if I have left anything out please let me know.
Thanks in advanced.
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dancerman
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Joined: 08 Jun 2006
Location: Atlanta

PostPosted: Fri Nov 17, 2006 3:03 am    Post subject: Reply with quote

I have never heard of carb cleaner for the outside of the engine. You may have damaged the electrical system by spraying all the connectors. Take them apart and make sure they are clean and dry. Do not put in another engine computer until you do this or you risk frying it also. Try other parts stores for the computer. I see Adv.Auto has them for the '99 model.
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spotter6
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Joined: 16 Nov 2006
Location: Schenectady,NY

PostPosted: Sat Nov 18, 2006 6:48 am    Post subject: Reply with quote

I thank you for the response, I have posted this on one other thread and have so far gotten no other input. I have to say that I posted this question with the hope of finding a quick answer but as we all know with all things medical and mechanical there is no quick answer. With that in mind I did have another trump card to pull, I consulted the oracle - my father who has been a mechanic by trade since god made dirt. As a typical son I just hate to ask him right away for help partly to learn for myself and partly because I don't like to make him travel to my home to work on something for me I'd rather it be to visit and relax.. Soo...Enough background lets address the issue...

So here is the prognosis:

Diagnosis = Failed ECM-'Yes my computer is hosed'

-> Carb and choke cleaner, if it doesn't say specifically such as with brake cleaner that it will damage electrical components can be used to clean electrical contacts since it is mostly a highly evaporative alchohol base and petroleum distilates. Not unlike WD-40...BUT and I express, IT IS NOT RECOMMENDED since it washes off any protective film accumulated on the contacts and wiring... As a rule if it's not visually corroded don't waste your time such as I did, it really accomplishes nothing. **** This however is not believed to be the cause of my problem, it more than likely did not kill the ECM****

->The ECM after locating it was visually corroded - AND - of course in the 99' it is located next to the air clear in on the drivers side. I did remove the air clear and used a high powered vaccum cleaner to remove debri from inside the compartment. The ECM was probably going bad already and the static electricity generated from the vaccum cleaner more than likely finished the job... Makes sense to me as I work with computers in my occupation (obviously I. R. not a mechanic Shocked ) and we constantly have to discharge static electricity very rarely do we use vaccum cleaning, its usually compressed air....

Soo..Since we are fast approaching a Holiday and I had to order the part I'll be waiting to finish this repair, so I'll finish my tune up and post my results when I finish....

Again, thanks for the response and I will do as you mentioned just to cover my a** and make sure everything is clean and dry and maybe even swab some dielectric grease on any trouble spots..

Happy Thanksgiving!!
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spotter6
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Joined: 16 Nov 2006
Location: Schenectady,NY

PostPosted: Sun Nov 26, 2006 12:10 pm    Post subject: Update Reply with quote

Hello All,

Well since my original post I just thought that I should update and post some results.

So far I have done the following:

Checked ODBII codes which gave a P1600 on my cheapie ODBII Reader and a P1694 on my fathers top of the line ODBII Reader. Checking the DTC Library P1600 doesn't exist and P1694 means. "No BUS Message Recieved From ECM Mod".

It was this error definition which prompted us to believe that the ECM Mod was hosed. SO I ordered a re-maned ECM and installed it. To my dismay and my dads disbelief nothing changed. Both, my amp/volts gauge and fuel gauge were still not working and the engine cranked but would not start.

So, after this disappointment I immediately went to work checking the two most important things you need for the engine to run Spark and Fuel.

I checked for spark on the #1 Cyl by disconnecting the plug, placing a screw driver in the end of it and setting it near "1/8 of an inch away from" a bolt head next to the valve cover. This test revieled no spark, so I did a bit of research and came up with two possibilities.

1.) The CPS - "Camshaft Position Sensor" - or more correctly the Stator or - "Pickup Coil" - was shorted out.

- OR -

2.) The CPS - "Crankshaft Position Sensor" - sensor had shorted out.

Yes, they have the same accronym and no they are not the same part. But, they both communicate with the ECM to regulate spark and fuel pulse.

So, based upon what I had done to get me in this mess I went to the part that would be the most pain in the arse to fix and replaced it first. Hey, it's been my experience that I try to do everything right including f**king things up.

Yep I went for the "Crankshaft Position Sensor" - which I have just finished installing and so far my gauges have come back to life. I now have an amp/volt gauge and my fuel gauge is now working again. I have not attempted to start it yet, but I would say prospects look good.

I guess the moral/'s to the story is don't clean electrical connections without letting them dry, unless you know what you've used is non-conductive or will not damage the contacts, and don't be so quick to replace the ECM.

I will post another update after I get up and running, but for now everything is looking good.

Thanks to everyone who have posted the usefull information in this forum, without it I'm sure I'd still be trying figure this one out.

Steve

'99 Cherokee Sport 4.0 IFI
Nothing special yet
P.S. It's not my Scout but it'll do..
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JeepinNH
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Joined: 13 Sep 2005
Location: New Hampshire

PostPosted: Sun Nov 26, 2006 1:57 pm    Post subject: sensors Reply with quote

Hello, a 99 does not have a Camshaft Position Sensor, only the older ones do. The crankshaft one sux to replace as you already know. Good luck.
_________________
Mike

Present: 99 Cherokee
Past: 86, 87 Cherokee; 94 Grand Cherokee
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spotter6
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Joined: 16 Nov 2006
Location: Schenectady,NY

PostPosted: Sun Nov 26, 2006 3:52 pm    Post subject: Another Update Reply with quote

Hello All,

Well, the verdict is in it was my Crankshaft Position Sensor. I didn't attempt to start it up untill I had finished my tune up and buttoned everything up.

But, when I did, it started up first time. No drag or hesitation. The check engine light stayed on for a minute or two but the ODBII scanned "no codes". After starting it a second time it went off after taking it out for a test ride down the highway, I'm thinking the new ECM needed time to read all the sensors on the engine.

**As far as the Camshaft Position Sensor I believe I already stated exactly what you were saying....
I was just pointing out that what many people on here refer to on Pre 2000's as the Camshaft Posistion Sensor is actually the Stator or Pickup Coil...
Infact even the Haynes Manual Calls it the Camshaft Position Sensor and then notes Pre 2000 models have a Stator instead...**

On a side note, my '79 Scout II had a terrible time with the Stator/Pick-up Coil burning out all of the time (it didn't have an accessory equiped ignition switch so listening to the radio without the engine running burned out). So we swapped it out with a Distributor which had a set of Points in it instead... I wonder if anyone has accomplished the same thing on the inline six?..

Anyhow, all is well and the beast lives.. Now I'm all geared up to throw a lift in it and any suggestions on what the best and least complicated kits are available?

Anyway, thanks again to everyone posting on this thread. All of the information here is top notch and a great help...

Steve

'99 Cherokee Sport 4.0 IFI
Nothing special yet
P.S. It's not my Scout but it'll do..
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dancerman
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Joined: 08 Jun 2006
Location: Atlanta

PostPosted: Mon Nov 27, 2006 2:45 am    Post subject: Reply with quote

Do you think you caused the sensor to fail by using the cleaner or just finished it off (you said you already had a CEL before the failure)?
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spotter6
Member


Joined: 16 Nov 2006
Location: Schenectady,NY

PostPosted: Mon Nov 27, 2006 6:19 am    Post subject: Reply with quote

It is hard to say that I actually caused it by using the cleaner.

Based on the fact that the injectors, throttle position, and air intake temp sensor were also cleaned/sprayed with the same chemical and are not damaged I doubt cleaning it in general caused it to fail.

I'm examining the sensor itself and the area where the wires enter sensor has what appears to be silicon sealant and mine is deteriorated to the point where moisture could enter. I'm betting the spray wicked down wire and entered the sensor through this area where it probably washed off any protective build-up and allowed it to finally short out completely...The sensor is obviously visually burnt and very corroded as well...

So, IMO it was already on the edge of malfuction (probably what the check engine light/ECM was indicating) and by spraying things down I finished it off.

Anyhow, on my new sensor I added a bit more RV/Clear Silicon to the area where the wires enter it, and used dielectric grease on the plug/connection to make sure moisture will not penetrate. This may seem like over-kill to some people, but sometimes a little extra care adds that ounce of prevention. As my dad says, "If you can't find the time to do it right how are you ever going to find the time to do it twice?"


Steve

'99 Cherokee Sport 4.0 IFI
Nothing special yet
P.S. It's not my Scout but it'll do..
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