Need Help!!!!

Hey guys, Im having a problem with my idle on my jeep. I have done a easy way HO to Renix swap and it has always ran well. It has been about 2 years now since the swap and now Im having issuse. It has a rough erratic idle and today it started to surge really bad when I take off. Also it will die on me somtimes because the idle gets so low. Im not sure where to start looking to fix this problem. Im good at basic stuff but not good at figuring out what to fix. Any help will help, thank you.

there's typically a valve that controls air intake for idle control. it's typically mounted on the throttle body. On fords, they're called idle air control valves. many times these get stuck or don't close fully from gunk or debris, and cause idling issues. basically, it creates a vaccum leak. you can clean this out with throttle body cleaner and q tips if you take it off. other than that, check for vaccum leaks elsewhere.

I went thru this with my 89 last year. New iac valve, cleaned throttle body, new bored out throttle body, tested sensors, searched for vacuum leaks, and lo and behold, egr solenoid was belly up and exhaust gasses in the combustion chamber at idle are not good.

Do you still have EGR after your swap?

Yes I still have the egr after the swap, all i did was swap everything from my old renix to the Ho motor. I found a clogged vaccum line and that really helped it out alot. But it still isnt running quite like it should though. I was thinking about the egr delete and then check sensors. Im gonna start digging into it more today.

What vac line is /was clogged?

TESTING THE EGR VALVE FOR 87-90 4.0 ENGINE
Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
***************

The clogged vaccum line was one of the ports on the back side of the airbox. Once i cleaned it out it was running better and not wanting to die on me anymore, but it still doesn't idle like it should. I will check the egr with the way you said to and post up what I find out. Thank you for the info.

Check the CCV hose from the back of the valve cover to the intake manifold. It too can clog/restrict causing a low/rough idle. What happened to one line coulda happened to another.

I checked the egr like you said and it seems to be working correctly. Im still searching the vaccum lines for leaks and other possible causes. The ccv hose is clear and working like it should as well. Still searching?????? Thank you for your input. If you think of anything else, let me know and I will check it out.

Check your TPS on the "engine" side per the following instructions next.

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: Set your meter to measure Ohms. 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 runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
If you see more than 1 ohm of resistance, and/or fluctuating resistance, 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 a three-wire TPS mounted on the throttle body.
This manual transmission vehicle TPS provides data input to the ECU. The manual transmission
TPS 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. Adjust the TPS until you have achieved this percentage. If
you can't achieve the correct output voltage replace the TPS and start over.
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--FOR 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.
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. If you have TRANSMISSION issues check the four-wire
connector side of the TPS. If you have ENGINE issues check the 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 03-13-2012