89 Limited 4.0 auto 4wd barely runs

[Cox89XJ]

Replaced tps and 02 sensor
Tests map and mts all good
It never runs good but barely runs when at operating temperature
I haven’t posted in years but I could sure use some help with ideas

 

[cruiser54]

Go to www.cruiser54.com and complete Tips 1,3,4, and 5.

Is the hose from your throttle body to MAP sensor on the firewall cracked, collapsed or otherwise messed up?

 

[Cox89XJ]

EGR diafram does not move when throttle is opened
When putting my finger on the end of the vacuum line going to the EGR I can feel vacuum and motor slows down when vacuum line is disconnected from EGR
When I move diefram manually engine will almost die
Would bad EGR cause engine to miss and puff back through intake?
Thanks so much I’ve found and cleaned a lot of stuff but it’s not fixed yet

 

[RCP Phx]

I would check the manifold vacuum first and see what it is? Then with a vacuum pump you accurately test the EGR diaphragm.

 

[Cox89XJ]

Yes I need to get a vacuum gage. With my finger on the end of the vacuum hose I could feel the vacuum fluctuating when opening the throttle

 

[Cox89XJ]

I bought this jeep in 2005 and it had 185k miles on it It now has 204k miles I only use it for my hunting vehicle
It just started this a couple months ago when I was using the winch to pull up 2 shrubs that had died I’m just now getting around to fixing it Thank y’all for your help

 

[Cox89XJ]

I’m at my wits end. The IAC, O2 sensor and EGR was bad. Besides them I’ve replaced the tps, and cps, cleaned the throttle body and ecu along with every connector I could find. Checked the MAP and it’s working. The jeep runs a little better but still missing and cough’s back through the throttle body when trying to accelerate. I don’t think a LS swap would be any worse than this.

 

[RCP Phx]

What basic engine testing have you done?

 

[Cox89XJ]

Like I stated, it started this while I was winching two dead shrubs from around the house. When operating a winch I keep the motor running to help keep the battery alive. While it was idling it went dead and has been messed up since. It is running a lot better now but not good.
I guess my next move is going to be replacing vacuum lines. I checked distributor cap and coil pack. Some component went bad all at once it seems to me. I’m open for suggestions

 

[Cox89XJ]

Used to turn the key to start and after 4 or 5 seconds it would crank remix don’t crank immediately
Now I have to mash the gas pedal for it to finally start

 

[cruiser54]

Mashing the gas pedal tells us it's very rich. That points to MAP sensor.

How did you check it?
Did you adjust your new TPS?

Is the vac line to MAP melted shut by chance? I've seen that.

 

[Cox89XJ]

When cleaning the throttle body I cleaned the vacuum line going to the map Also when vacuum line is unplugged jeep almost dies
I found a bad coolant temperature sensor at the bottom of the engine The sensor plug broke when I tried unplugging it would that cause the problem? I will have to drain the coolant to replace it

 

[RCP Phx]

I found a bad coolant temperature sensor at the bottom of the engine The sensor plug broke when I tried unplugging it would that cause the problem?

The CTS is located on the rear of the cylinder head, but a bad CTS will cause the motor to run rich.

 

[Cox89XJ]

I’ll get a coolant temp sensor.
Checked the map again
C - 4.8 volts with engine off and key on
B - 4.8 volts with engine off and key on
B - 1.75 volts with engine on and up to operating temperature

 

[Cox89XJ]

There are 2 coolant sensors on a renix. one for dashboard where you mentioned and one at the bottom of the block on driver side that sends a signal to the ecu. If I’m wrong on this someone let me know

 

[Cox89XJ]

Finally got time to work on the jeep
After replacing some bad parts I found what was wrong. The fuel pump would only build up to 18 psi Replaced with new one. The old one was leaking at a flexible hose but I was not about to put the old one back on I had replaced the fuel pump 18 years ago but it’s only been driven less than 20 thousand miles so that’s why I didn’t check fuel pump first and I should have.

It runs great now. Parts replaced ITS, TPS, O2 sensor, replumbed the vacuum line going to the MAP sensor, cleaned throttle body, replaced vacuum lines and replaced fuel pump.
I would like for this post to help someone so if someone can bump it up

 

[Cox89XJ]

Thank you Cruiser for your info. There’s still some of your helpful information that I need to do

 

[Hypoid]

There are 2 coolant sensors on a renix. one for dashboard where you mentioned and one at the bottom of the block on driver side that sends a signal to the ecu. If I’m wrong on this someone let me know

Two sensors for RENIX, that is correct information.