Stalls On Acceleration

[LarryH88bt]

88 4.0, auto.  I tried some things to get my fuel gauge to work, mostly playing with ground wires and cleaning the big c101 connector above the brake master cylinder, and the engine started idling high, about 2k plus.  I let it sit a few hours, came back and cleaned out the throttle body that wasn't dirty, shot some carb cleaner into the vacuum lines, removed and cleaned the TPS and idle switch.  idles a little rough but it always has,  Still stalls when I press the throttle.  It doesn't die completely but it's damn close before it catches up and revs. 

 

When it was idling high it was doing the exact same thing it did when I ran it with the EGR disconnected and the port open.  It sounded the same, there was an audible sucking sound from the engine bay.  I have to suspect the EGR again.  If I take off the intake and just have the throttle body open and I pull on the throttle cable, I can hear the EGR briefly, and then the revs pick up.

 

EGR or something different? 

 

 

 

[cruiser54]

Check to be sure your intake manifold bolts aren't loose. A vacuum leak can be found by spraying throttle body cleaner around suspect areas with the engine at an idle.

 

Cleaning the TPS usually spells sudden death for it bTW.

 

Did you get the TPS lever back on the correct side of the linkage?

[LarryH88bt]

Intake manifold bolts, have not tried that yet.

 

Well I guess I shouldn't have said cleaned the TPS since it doesn't come apart I just cleaned the connectors.  The lever goes on top. 

[LarryH88bt]

Manifold and valve cover bolts were a tiny bit loose but I did indeed put the TPS back in wrong.  So that was the problem.  However.... there is still a slight hesitation before the revs pick up but it doesn't stall out.  Any ideas on that?

[fiatslug87]

Is the TPS adjusted correctly and are you sure there is no "dead spot" in the TPS?

 

 

Here's how to check the EGR system

 

 

[LarryH88bt]

So that's why the TPS has slotted bolt holes :eek: .  I'm sure it is not adjusted correctly.  Not sure what you mean by a dead spot.  I'm out of town for the next 10 days so it will have to wait. 

 

Thanks for the response. 

[fiatslug87]

The TPS is basically a potentiometer, as the throttle opens it sweeps the TPS which adjusts voltage. As it moves the voltage should change, I had one where during a portion of the sweep the voltage did not change and then abruptly changed, that's what I call a dead spot.

[cruiser54]

So that's why the TPS has slotted bolt holes :eek: .  I'm sure it is not adjusted correctly.  Not sure what you mean by a dead spot.  I'm out of town for the next 10 days so it will have to wait. 

 

Thanks for the response. 

Yes. But the factory has you adjusting the TPS on the Trans side connector. No bueno unless you're troubleshooting a trans/shifting issue.

 

Use the instructions below:

 

 

RENIX TPS ADJUSTMENT

Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.

IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.

MANUAL TRANSMISSION:

RENIX manual transmission equipped XJs have only a flat three-wire TPS mounted on the throttle body and it provides data input to the ECU. It has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you

have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over.

Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.

AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles, as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.

FOR AUTOMATIC TRANSMISSION RELATED ISSUES: Check the square four-wire connector side of the TPS.

If you have ENGINE ISSUES check the flat three-wire connector side of the TPS.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.

Revised 09-22-2012

[LarryH88bt]

I got the TPS close as I could which must mean it's no good.  The A-B reference was reading 10, the best I could get the B-C was 1.3.  It runs okay, I don't really want to throw money in to it right now.

[cruiser54]

I got the TPS close as I could which must mean it's no good.  The A-B reference was reading 10, the best I could get the B-C was 1.3.  It runs okay, I don't really want to throw money in to it right now.

It's history.

[Ellman605]

I don't know if you checked but i accidentally didn't put the butterfly lever on the TPS under the throttle lever. That was a brain fart I had but I had the same issue and that fixed it for me.