zj when floored wont rev past 3000 rpm power is still there - Page 2 - JeepForum.com

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post #16 of 43 Old 08-17-2009, 11:44 AM
PlazJ
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What do you mean exactly by "Converter is gutted"

Hopefully we can find some common issues that helps serveral of us here.

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post #17 of 43 Old 08-17-2009, 12:14 PM
Yardman Harry
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I had this problem!! In park I could floor it, I could bring it up to red line if i wanted to.

But, if i put a load behind the jeep, like 4 or 5 passengers, or bikes on the top, or just me and my wife going up a hill the jeep acted like it was hitting a rev limiter at around 3000 rpms. I even threw a code here and there, dont remember the code number but it was telling me that my mix was too lean.

I tried everything, from new coil, fuel filter, dropped the fuel tank and cleaned it out, cleaned the TB... the list goes on.

Turned out to be the TPS. I changed the TPS out with a brand spankin new one, problem solved.

Yard

1996 Jeep Grand Cherokee. V8 - 5.2 litre 242 SelecTrac. SURCO Safari Roof Rack
Hunter Green


1997 Jeep Wrangler Sahara Ed. I6 - 4.0 litre, 4" SL, D44 rear, 4:56 Gears, AA SYE with double cardon custom rear Drive Shaft, IRO Adj CAs, Kevins Rear Adj TB with JOHNNY JOINT end

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post #18 of 43 Old 08-17-2009, 06:36 PM
veddersbetter
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Quote:
Originally Posted by PlazJ View Post
What do you mean exactly by "Converter is gutted"

Hopefully we can find some common issues that helps serveral of us here.
Converter body is still there...internals are ripped out. Straight through
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post #19 of 43 Old 08-17-2009, 07:42 PM Thread Starter
tige_tower
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well i fixed my problem and i dont kno how i disonected the cps and pluged it back in n worked like a dream... but it also dawned on me that my jep has a remote start and the light was solid and wen that light sayed on solid is wen it was acting up but i disconected tnhe battery and reset it and the light wen away and it runs like a dream....as for y i revpast 3000rpm i tow a 2008 tige 20v that weighs about 5000lbs with a full tank of gas and core weight and u will not get ne were on the high way doin 1500rpm sorry but then again i do tow my boat doin 80mph down i-25 passin up powerstrokes and duramaxes but ya my problem is solved
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post #20 of 43 Old 08-17-2009, 08:16 PM
PlazJ
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Before I give a quick update I wanted to throw in the short story on my Grand Cherokee. I bought this used with most of the engine bay hardware removed and the engine partially disassembled. I did some more tear down and installed a complete gasket kit, heads and all, as I put it back together. I've had to learn alot and check every system on this rig as I go because I don't know the previous condition or history of any thing. So now it's running, but here we are solving other things along the way like many others.

Ok, on to the update... I tested my throttle position sensor and it tested fine. I had also previously cleaned the idle position sensor which lower standing idle from 1000rpm to a smooth 500-600 rpm. **After rerouting the coil and plug wires away from each other and away from the exhaust manifolds suggested by five.nein, things are running noticably better. I'm now able to rev up to 4500 rpm before it seems to hit a limit, grunt a bit, then return back to idle pretty smoothly. Before the wire re-routing it was an ugly run up to 3000 max. I purchased some wire separators/stand offs to make the wire placements permanent, but not had a chance to install them yet. Things may be even better after I clean things up a bit more.

I don't have time tonight, but I want to make a new post detailing all of the things I've done so far to get this running again and some of the other things I've learned along the way that may help others track down problems.

Now that I'm able to get the revs up more where I think they belong, another issue arises. When I put it in gear, it wanted to stutter and die and I couldn't get the rpms up again above 2500-3000 with out lots of sputtering. This turned out to improve when I added the right amount of transmission fluid. I had checked this earlier in the week and thought it had enough fluid. But after running through the gears with the parking brake on and rechecking, there was no ATF oil on the stick. I added two quarts that had handy, and I was able to move the Jeep up and down the drive way relatively well. I've not confident enough yet to take it out for a test drive. It needs more tranny fluid, and it still want's to stumble badly around 800-1100 rpm.

I add this last bit because it seem at least in my case that a poorly functioning tranny can cause the engine to suffer and limit the rpms when it's in gear even if it's not moving.
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post #21 of 43 Old 08-17-2009, 08:19 PM
PlazJ
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Quote:
Originally Posted by tige_tower View Post
well i fixed my problem and i dont kno how i disonected the cps and pluged it back in n worked like a dream...

CPS? Crankshaft postion sensor? I haven't checked the one on mine yet.
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post #22 of 43 Old 08-17-2009, 08:21 PM
PlazJ
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BTW, I posted a quick how-to on testing the TPS over here if any one needs it.

http://www.jeepforum.com/forum/showp...27&postcount=7
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post #23 of 43 Old 08-18-2009, 08:32 PM
veddersbetter
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Checked TPS with a voltmeter. (This is a TJ btw) It reads .9 at idle and when I rev it goes to 1.8 tops. The link says it should be 3.9 - 4.5. It does go up smoothly and Im revving to around 3000+RPM as far as I can tell (revving under hood)
Does this sound like a problem?
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post #24 of 43 Old 08-19-2009, 05:41 AM
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Quote:
Originally Posted by veddersbetter View Post
Checked TPS with a voltmeter. (This is a TJ btw) It reads .9 at idle and when I rev it goes to 1.8 tops. The link says it should be 3.9 - 4.5. It does go up smoothly and Im revving to around 3000+RPM as far as I can tell (revving under hood)
Does this sound like a problem?

I pulled this from the 97 TJ FSM.

With the ignition key in the ON position, check the
TPS output voltage at the center terminal wire of the
connector. Check this at idle (throttle plate closed)
and at Wide Open Throttle (WOT). At idle, TPS output
voltage should must be greater than 200 millivolts.
At wide open throttle, TPS output voltage must
be less than 4.8 volts. The output voltage should
increase gradually as the throttle plate is slowly
opened from idle to WOT.

You should turn your engine off, and put the key position to on. Try the test again. If the test fails, then you have a bad TPS.

(sounds like you have a bad tps though... )

Yard

1996 Jeep Grand Cherokee. V8 - 5.2 litre 242 SelecTrac. SURCO Safari Roof Rack
Hunter Green


1997 Jeep Wrangler Sahara Ed. I6 - 4.0 litre, 4" SL, D44 rear, 4:56 Gears, AA SYE with double cardon custom rear Drive Shaft, IRO Adj CAs, Kevins Rear Adj TB with JOHNNY JOINT end

1999 Mazda Miata MX5 - Jet Black

1990 Jeep Cherokee Sport I6 - 4.0 litre
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post #25 of 43 Old 08-19-2009, 10:39 AM
veddersbetter
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Thanks Yardman...If Im reading this right I do this with the Engine OFF and the Key ON. That would make sense
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post #26 of 43 Old 08-19-2009, 06:54 PM
PlazJ
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Yeah that sounds to low. One other check the service manual says to do is pull the TPS connector and check the voltage between pins 1 and 3 (two outside pins). It should be 5 volts. If that voltage is correct, then it may be a bad TPS. It that voltage is wrong then it has you check the wiring/connection to the powertrain control module and the PCM itself. I imagine the only way to check the PCM is to have a spare.
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post #27 of 43 Old 08-19-2009, 07:05 PM
PlazJ
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My problem has morphed a bit. Now that the coil and plug wires are rerouted, I can run the RPM's past 3000 and up to red line *IF* I do it slowly. If I give it to much accelerator all at once, it runs rough, tries to stall and backfires. Though I started with an EGR and coolant error initially, those are fixed and I don't have any additional error codes at this time. I know some vehicles have to run so many cycles or miles before setting error code, so maybe it just hadn't had time to set any new codes yet.

The only two sensors I haven't tested or replaced yet are MAP and CPS. I here the crankshaft sensor is a bear to get to on the 5.2, guess I'll be finding out shortly. Any one know if the mass air flow sensor can be tested while running? I'll have to scan the manuals on that one.


*Edit Oh yeah, there's still the O2 sensor. How does your Jeep react when that's bad? When I've had these go bad on other type vehicles, but those ran rich and lost a little power. They didn't start choking and backfiring like this one.

Last edited by PlazJ; 08-19-2009 at 07:29 PM.
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post #28 of 43 Old 08-20-2009, 05:44 PM
veddersbetter
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Checked my TPS today with key on engine off. 0.9-4.09 WOT. Went up and back down smoothly.
(It is a 5 speed ..4.0L...to narrow it down)

Last edited by veddersbetter; 08-20-2009 at 06:02 PM.
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post #29 of 43 Old 08-20-2009, 05:48 PM
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I had this problem on mine when I would drive it I couldn't get it to rev past 3,000 RPM it would always shift at that RPM no matter what. I slightly adjusted the tranny cable on top of the engine and it got better.

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post #30 of 43 Old 08-20-2009, 07:01 PM
PlazJ
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Looks like I'm not making much progress. I'm still struggling to get the rpms up and there's backfiring from the exhaust if I give it too much throttle all at once. It's even worse if I put it in gear. Still no error codes.

I pulled the PCM and cleaned reset the connector and pins. You can't do much else with it as the internals are incase in a transparent rubbery glue. Didn't help. Wish I had a spare to test, those are kind of expensive if it does't wind up fixing the problem.

Can any one point me to the CPS on the 5.2? I think it's supposed to be on the back of the block/bellhousing on the passenger side, but I can't seem to find yet.
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