99 cherokee is about to go to the crusher!
09-18-2009, 05:05 PM
#1
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99 cherokee is about to go to the crusher!
I did some searching and came up with all the answers I already tried so I thought I would ask you guys.
Im working on a 99 cherokee sport with the 4.0 and an auto trans. I have replaced the crank sen, cam sen, tps, and have gone over the entire thing twice. It will run, but only if you hold the throttle wide open. It has fuel, and good spark. Im at a loss, I have no idea what to do next. I know that 90% of the time the problem is the cps but this one is fine, any other ideas?
Im working on a 99 cherokee sport with the 4.0 and an auto trans. I have replaced the crank sen, cam sen, tps, and have gone over the entire thing twice. It will run, but only if you hold the throttle wide open. It has fuel, and good spark. Im at a loss, I have no idea what to do next. I know that 90% of the time the problem is the cps but this one is fine, any other ideas?
09-18-2009, 05:09 PM
#2
Stop throwing money at it! Once your heep gets a taste it won't stop eating it!!!!
1.) Gas Pressure test
2.) Thoroughly clean the throttlebody, IAC, MAP Sensor tube and passage
3.) Check for vacuum leaks
Report your results and lets go from there. Deal?
1.) Gas Pressure test
2.) Thoroughly clean the throttlebody, IAC, MAP Sensor tube and passage
3.) Check for vacuum leaks
Report your results and lets go from there. Deal?
09-18-2009, 07:18 PM
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Every thing is clean, I pulled it all off and made sure of it. I went to the part store and rented the $160 pressure tester, its between 48 and 49psi. I know that's a little high, but I don't see how that would make it run like this.
09-18-2009, 08:04 PM
#5
Actually it's right on the money, spec's are 49 +/-5psi.
I'm going to say the TPS may not have been properly installed and yes I've screwed the pooch doing it myself a time or two. Here's why I think it's TPs related:
Got a multimeter? (Just say yes so as I ain't gotta flame ya for being tool deficient....ok?) Right, so here's what ya do:
Or you can skip that part and go straight to this:
I provided a super secret hint that will require a keen eye and goobs of intelligence to decypher.
Once again, post up and keep us informed.
I'm going to say the TPS may not have been properly installed and yes I've screwed the pooch doing it myself a time or two. Here's why I think it's TPs related:
Along with inputs from other
sensors, the PCM uses the TPS input to determine
current engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
sensors, the PCM uses the TPS input to determine
current engine operating conditions. In response to
engine operating conditions, the PCM will adjust fuel
injector pulse width and ignition timing.
THROTTLE POSITION SENSOR (TPS)
To perform a complete test of the TPS (Fig. 37) and
its circuitry, refer to the DRB scan tool and appropriate
Powertrain Diagnostics Procedures manual. To
test the TPS only, refer to the following:
The TPS can be tested with a digital voltmeter.
The center terminal of the TPS is the output terminal.
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 be greater than .26 volts but less
than .95 volts. At wide open throttle, TPS output
voltage must be less than 4.49 volts. The output voltage
should increase gradually as the throttle plate is
slowly opened from idle to WOT.
To perform a complete test of the TPS (Fig. 37) and
its circuitry, refer to the DRB scan tool and appropriate
Powertrain Diagnostics Procedures manual. To
test the TPS only, refer to the following:
The TPS can be tested with a digital voltmeter.
The center terminal of the TPS is the output terminal.
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 be greater than .26 volts but less
than .95 volts. At wide open throttle, TPS output
voltage must be less than 4.49 volts. The output voltage
should increase gradually as the throttle plate is
slowly opened from idle to WOT.
INSTALLATION
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 47). The TPS must be
installed so that it can be rotated a few degrees. (If
the sensor will not rotate, install the sensor with the
throttle shaft on the other side of the socket tangs).
The TPS will be under slight tension when rotated.(1) Install TPS and retaining screws.
(2) Tighten screws to 7 N·m (60 in. lbs.) torque.
(3) Connect TPS electrical connector to TPS.
(4) Manually operate throttle (by hand) to check
for any TPS binding before starting engine.
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 47). The TPS must be
installed so that it can be rotated a few degrees. (If
the sensor will not rotate, install the sensor with the
throttle shaft on the other side of the socket tangs).
The TPS will be under slight tension when rotated.(1) Install TPS and retaining screws.
(2) Tighten screws to 7 N·m (60 in. lbs.) torque.
(3) Connect TPS electrical connector to TPS.
(4) Manually operate throttle (by hand) to check
for any TPS binding before starting engine.
Once again, post up and keep us informed.
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