seeker1340

1997 Cherokee 4.0 Auto. 214K miles. Intermittent stalling / flooding?? and difficulty starting. Usually occurs when the jeep is cold. When I come to a stop sometimes it starts to die. Then, I put it in neutral and rev it to prevent a stall. The engine responds as if it were flooded running rough with a delayed response. Once it starts to clear, as I rev it, the rpm stay high for about 10 seconds then it slowly idles down. After a stall incident it takes about 10 minutes of driving before the engine idles normally. If I turn the jeep off without really heating up the engine after a stall, then to get it started I have to hold the pedal on the floor before it will fire. Just like it was flooded. Also, if I let it die when its idling rough, I have to hold the pedal on the floor to get it started. Recently tuned up. Idle problem is starting to become more common. No check engine light. Any ideas on where to start?

azhobo

I had the same problem, took a while to find my problem, but tracked it to an "open" temperature sender. Seems to be some confusion about which is what here, I'm talking about the one on the T'stat housing.
I was having a problem with the engine stalling during idle, more specifically when trying to leave from a red light or stop sign. Seemed to be floooding, and would restart with no problem after a few minutes of cooling. I found the temp sender to be intermittently open, which after doing some reading I found to mean the computer was being told the ambient temp was -40 degrees F. At that temp the computer was going to full enrichment and flooding the engine. I also found a second problem with the two wire connector, one wire was only connected by 2 or 3 strands, which made for an even higher ohm reading to the computer. If you decide to look in this area, make sure you check the 2 pin connector to your sending unit. If you have a loose connection there, it would also be seen as extremely low ambient temp by the computer. A normal ohm value of a good sensor should be no more than about 8K ohms.

HTH
Bob

jmaxj

sounds like the TPS is junk

F1Addict

The problems you've described could be caused by a number of things so it's a process to exclude some of them. Could be a fuel delivery problem so that's the fuel pump, injectors, fuel filter, fuel pressure regulator. I think there's a test for the pressure regulator, you can usually hear the pump prime before your start which isn't a guarantee that it's working properly but from what I've read, they usually work or don't work, there's rarely an in between. The filter is easy, $15 at your local parts store and 15 minutes in the left rear wheel well. Plus, you'll smell of gasoline for the next three days so everybody knows you're handy. You can brag about what an ordeal it was, even though it's a pretty simple but messy job.

Vacuum lines, check them all. A vacuum leak can cause all kinds of funky stuff.

CPS (Crank Position Sensor), if you haven't replaced it, it's probably time. Again, not too expensive ($40-$50) but they are a pain in the **** to get to. They're also prone to failure and produce many of the symptoms you've described. Your CPS can be tested by unplugging it from the harness and probing the two leads (A and B) with a multi-meter set on AC volts (not DC), with someone cranking the engine (it won't start) you should read ~.5v AC, if it's >.35v then it's time to replace. CPSs can go bad all at once or die a slow and painful death so it's something to look into.

seeker1340

Measured resistance across the leads of the temp sensor in the thermostat housing @ 21.9 k ohms @ 55 deg F. Which according to the manual is pretty close for that temp. Also, cleaned the leads (some corrosion). The wire and connector are in good shape. Drove it. So far cannot reproduce the problem. But that is how it has been with this issue. For a week its fine then suddenly it will try to flood out at a stop. So far, when it floods its been within the first 30-40 min of driving. It has not happened after the engine has thoroughly warmed up. Also, I think its flooding because to restart it I have to hold the pedal to the floor and rev it for a couple minutes until it clears. I checked for error codes and while I did not have a check engine light I did have a 17 which says the engine was too cold for too long or something. After I ran a few errands, I disconnected the temp lead and received a CEL immediately. Also, there was no difference in how the engine ran. I was hoping that it would re-create the problem but it did not. Thanks to all for the replies so far.

seeker1340

I measured the temp sensor a few more times and the resistance was a couple hundred ohms low for the temp. I replaced the temp sensor. So far, no problems. Thanks for pointing me in the right direction azhobo.