2.3L ('83-'97) Idle surge, sometimes dies

[Jtrussell1890]

96 XLT 2.3l Lima 5spd, engine, regardless of temp, will fluctuate the idle between 300 and 900 and doesn't level out. I have replaced all 8 plugs and wires, air filter, oil filter, IAC, PCV and fuel filter. I have seen a few other threads refer to possibly TPS or MAF, but no info on how to test them before I just go throwing parts at a problem. The things I have done up to this point were already scheduled to be done any way. If I don't keep the throttle slightly depressed at idle, it will slow down enough that it dies. Can any one point me to a spec sheet or a guide of how to test the TPS and MAF and what readings I should be showing from my scan tool read outs?

 

[franklin2]

TPS at idle should be less than 1v output. When it's idling, what happens when you unplug the wiring plug to the IAC? It should keep idling very slowly. If it dies, you might need to tweak the idle stop screw open a little bit. Just don't go over 1v at closed throttle.

 

[Jtrussell1890]

TPS at idle should be less than 1v output. When it's idling, what happens when you unplug the wiring plug to the IAC? It should keep idling very slowly. If it dies, you might need to tweak the idle stop screw open a little bit. Just don't go over 1v at closed throttle.

After looking into this and also checking the MAF sensor, what I found was the MAF is bad. When I went to physically examine it, you could tell that it had been previously tampered with. The screws holding it in had been cross cut with a cutting disc to make them accessible with a flat head screw driver. The wire in the tip of the sensor was damaged (one of the coiled ones that reads air flow). Time to replace it. The TPS is reading properly and even showing correct % load on my scan tool. Every thing else, according to my scan tool, is in the nominal range and I did see a stored code for a fault in the MAF circuit.

 

[franklin2]

What type of scan tool do you use?

 

[Jtrussell1890]

What type of scan tool do you use?

I don't remember the brand off hand (will look when I get home in the morning), but it's nothing fancy. I mainly use it for codes and basic diagnostics. It also allows me to record a graph of what's going on for about 2 minutes and I can transfer it to a PC and print it or save it. It was like $35 or $40. It's no snap on or otc, but it does basic stuff I need.

 

[Jtrussell1890]

What type of scan tool do you use?

The brand is called Vident, but I didn't look at the model number.

Update to my issue, the replacement MAF fixed the issue. Took nearly 5 whole minutes to replace it once the part came in. Runs like a brand new truck now. So to recap what I've done this far:

Full tune up (8 plugs, wires and coil packs)
Head gasket
Oil change (one after the head gasket, then flushed engine 500 miles after that and changed it again)
Air and fuel filters
Center support bearing
Middle and rear u-joints

What's next:
TDI diesel swap
2"body lift with leveling kit
Custom center console for in dash touch screen infotainment system
New bed
Core support and front clip replacement
D/S front fender replacement
Upgraded head and tail lights
Upgraded instrument cluster
Upgraded seats
Update front suspension (ball joints, tierod ends, A-arm bushings)
New windshield
Reseal rear window
Repaint with new color and graphics