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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Thu Oct 17, 2013 4:26 pm Post subject: Cascade Jeep Tech! |
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maybe since were also a jeep forum now, maybe you guys can help me.
It's an '88 Cherokee 4.0L Renix with 173k on it, replaced some grounds and replaced TPS due to high-idle problems on warm start-up. I also had done an ignition tune-up and more recently a fuel filter.
TPS cured the high idle problem, yet I seem to have a new issue since I replaced it, very hard cold starts, the jeep idles rougher, seems to be slightly down on power, and occaisional stalls when idling in gear cold (such as after coming to a stop, acts like someone shut off the key)
You guys think defective TPS? or maybe its fluke that this all happened after replacing TPS? _________________
'88 FORMULA |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Thu Oct 17, 2013 5:05 pm Post subject: |
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Hook a volt meter to the tps signal and check it. Best if you have a graphing meter. You're looking for dropouts while you cycle it through its range. |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Thu Oct 17, 2013 7:57 pm Post subject: |
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Is this an adjustable TPS? |
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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Thu Oct 17, 2013 8:30 pm Post subject: |
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This is an adjustable one.. I have adjusted it a few different ways without feeling or noticing much difference.
I need a new volt meter that doesn't read 2-3v too high to check it out. |
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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Fri Oct 18, 2013 8:36 am Post subject: |
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Just noticed a new symtom last night, now suspecting something spark related. I started it last night and got up to 45mph without much warm-up time like it usually gets.
Right after it shifted into O/D it has a dead miss that jerks the whole rig at cruise speed. Doesn't seem to do it when warm though |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Fri Oct 18, 2013 11:31 am Post subject: |
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Crank sensor? They're a known jeep issue. |
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Dewey316 The Lama
Joined: 08 Jan 2004 Posts: 7295 Location: Bringing the tech
1990 Chevrolet Camaro RS
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Posted: Fri Oct 18, 2013 11:35 am Post subject: Re: Cascade Jeep Tech! |
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Come on Brandon, you didn't point out the obvious.
fiveoformula wrote: | Renix |
'nuf said. hahahah |
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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Fri Oct 18, 2013 1:04 pm Post subject: |
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chevymad wrote: | Crank sensor? They're a known jeep issue. |
Thats my thought too.... I'll still check the TPS also though. |
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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Fri Oct 18, 2013 1:48 pm Post subject: Re: Cascade Jeep Tech! |
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Dewey316 wrote: | Come on Brandon, you didn't point out the obvious.
fiveoformula wrote: | Renix |
'nuf said. hahahah |
Hey now! there are tons of them still on the road! |
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Dewey316 The Lama
Joined: 08 Jan 2004 Posts: 7295 Location: Bringing the tech
1990 Chevrolet Camaro RS
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Posted: Fri Oct 18, 2013 1:49 pm Post subject: Re: Cascade Jeep Tech! |
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fiveoformula wrote: | Dewey316 wrote: | Come on Brandon, you didn't point out the obvious.
fiveoformula wrote: | Renix |
'nuf said. hahahah |
Hey now! there are tons of them still on the road! |
The rest of them made it home. |
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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Fri Oct 18, 2013 2:05 pm Post subject: |
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Oh whatever... Its a classic! I still have the original "AMC" keys to it. Nothing chysler about it. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Oct 18, 2013 5:00 pm Post subject: |
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Actually, the Renix models are more reliable, just tougher to fix when they do break.
That one shouldn't have a crank sensor, it should still be distributor. Make sure TPS is good, then verify fuel pressure.
Map sensor vacuum line is known to break. _________________ A redline a day keeps the carbon away! |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Fri Oct 18, 2013 5:15 pm Post subject: |
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They have both a crank sensor and a distributor Paul. Distributor is just a cam sensor and spark distribution device. The crank sensor triggers the ignition and timing of the motor. |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Fri Oct 18, 2013 5:18 pm Post subject: |
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Oh and Paul's right about the renix. They work pretty well, just suck to diagnose or buy parts for. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Fri Oct 18, 2013 5:18 pm Post subject: |
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Really? I don't remember seeing one on mine. If that's the case, yes put a crank sensor on it. _________________ A redline a day keeps the carbon away! |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Fri Oct 18, 2013 5:52 pm Post subject: |
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It's hidden upper drivers side of the bellhousing. Jeep used an oddball flywheel trigger too, which is why most aftermarket ecm's like megasquirt don't work. |
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QwkTrip 11sec Club
Joined: 17 Feb 2004 Posts: 3942 Location: Peoria, IL
1989 Pontiac Firebird
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Posted: Fri Oct 18, 2013 7:55 pm Post subject: Re: Cascade Jeep Tech! |
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Dewey316 wrote: | The rest of them made it home. |
OHHHHHHHHH! Little sizzle on the grill. |
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fiveoformula Member
Joined: 08 Aug 2007 Posts: 1799 Location: OR
1988 Pontiac Formula
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Posted: Fri Oct 18, 2013 10:03 pm Post subject: |
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Yeah the crank sensor seems to make all kinds of crazy driveability problems when they start going out.. On the HO's and renix from what I read... The renix jeeps seem to have had under-engineered grounds from the factory that cause intermitten weird problems now they're old and falling apart. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Sat Oct 19, 2013 12:42 am Post subject: |
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Bah that's over analysis by the forums. My 87 had 278k and I don't think the grounds were ever touched.
Any make with a faulty ground willl cause issues. _________________ A redline a day keeps the carbon away! |
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DBL_TKE Member
Joined: 28 Feb 2007 Posts: 1505 Location: Aloha, OR
1991 Chevrolet Camaro Z/28
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Posted: Sat Oct 19, 2013 10:43 am Post subject: |
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fiveoformula wrote: | Just noticed a new symtom last night, now suspecting something spark related. I started it last night and got up to 45mph without much warm-up time like it usually gets.
Right after it shifted into O/D it has a dead miss that jerks the whole rig at cruise speed. Doesn't seem to do it when warm though |
Sounds exactly like what my Camaro started doing when i installed my most recent distributor. |
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