Jeep Strokers

Hey guys,
Okay, more "test" info. I went for another drive and I'm now driving it a bit more aggressive. I noticed that at about 1500 rpms, when I let off the throttle, the tac swings up and down about 500 rpms, but the road speed slows gradually, as would be expected. It seems to do this less at higher rpms/roadspeeds. Is this partially just from the fact that it's an automatic and that's the effect of the torque convert? I'm using the 4wt crank, so I understand that that there's less flywheel effect. The sensation in vehicle is as though the power is an electric switch that's flicked on and off very quickly. With the old 4.0, sometimes I'd do a 50-60 mile freeway drive, get in to a town and drive low speeds for a bit, and when I'd park and shut it off, sometimes it'd be VERY hard to start. Also it would sometimes rev up afetr similar conditions at drive throughs. On today's drive, after it would act up, when I would come to a stop, the rpm's would stay up at about 1000 for a brief bit. It has been idling about 700-750 rpms. Are the TPS and the VSS effected by increased temps? My old 4.0 used to run a bit hot, so it's possible that if these are thermally sensitive, they may be crappin' out. Otherwise, it feels great.

Thanks for the help,
crust1

Hey guys,
Here's another slightly tough one. I checked the plugs and I don't have pic to show, so I'll try to describe them. #'s 1,2,5,6 plugs have a strip about 1/4" wide from the top of the insulator up in to them beyond the base ring. #'s 3,4 seem to be light tan all over from about 1/3 of the way from the tip of the insulator up in to the plug past the base ring. The strip on #'s 1,2,5,and 6 is reddish at the tip of the insulator and ends up tan/caramel colored beyond the base ring. The heat strap has a blue-ish line about 1/4" towards the tip from the base ring. For reference, I have the MSD al6 brain, Blaster off-road coil, and the 8.5 MM wires. It does the triple spark below 3000 for 20 degrees of crank rotation, if I remember correctly. Do any of you know, on this subject, when I upgrade with a UniChip, does it have control over ignition timing, or should I get some sort of control accessory from MSD to allow for this?

Thanks all, I appreciate your knowledge and input,

crust1

When your seeing the RPM gauge jump up and down approx 300 RPM's if you listen real close, can you hear the engine revving with it? Does it almost act like your barely pushing the gas and letting off but the transmission never has time to downshift to move faster?

If so i have the same problem in my '90 (non stroker). I have still yet to figure out what is causing it. I've always called it "RPM Float", but maybe "RPM Surge" is a better term. A new TPS may help, but it didn't help me as the problem is still there. What is the output voltage from the TCU to the TPS? Its suppose to be 5v, but mine is down to like 4.65v. The wiring is good, my reading was taken directly at the TCU. (and verified at the TPS). My next step in my diagnostic procedure was to try a different TCU. FWIW, my Jeep has all new sensors that test within spec.

Ill be following your outcome to see what you find. If i find anything ill be sure to let you know... however in your case if you have not replaced the TPS, i would recommend you do so.

hmmm sounds like normal behavior to me... When you quickly let off the throttle on an Auto the idle air controller kicks in I think to keep things smooth and I think it also takes a moment for the engine to use up the extra fuel so you also have a bit of rich condition for a moment... I'd have to pay attention to mine to say for sure but I want to say this is normal behavior and mostly a result of abruptly letting off the throttle. maybe not though.

crustodd wrote:Hey guys,
Okay, more "test" info. I went for another drive and I'm now driving it a bit more aggressive. I noticed that at about 1500 rpms, when I let off the throttle, the tac swings up and down about 500 rpms, but the road speed slows gradually, as would be expected. It seems to do this less at higher rpms/roadspeeds. Is this partially just from the fact that it's an automatic and that's the effect of the torque convert?

That isn't how an auto should operate. If you let off the gas and the pedal drops to 500 then jumpt to 800 and stays there that can be considered normal, but to swing up and down 500 RPMs like it is surging is not. Anong with your description of the RPMs staying at 1000 for a brief bit seems to point to the TPS acting up. When I installed my stroke I had a similar situation on my TPS... with then engine off it would display the correct readings abut when driving it seemed to stick.. going off my Apexi's display it seemed to stick at 10... replaced it the same day and the weird behavior went away.n

crustodd wrote:Hey guys,
Here's another slightly tough one. I checked the plugs and I don't have pic to show, so I'll try to describe them.

I know nothing about the MSD systems other than they are not needed on our engine, but what I do know is that for you to properly read the plugs it must be immediately after a WOT run... i.e. Shoot up a hill under full throttle and when you let off the pedal, shut it down and coast to the side of the road.. then read or change your plugs there for reading later. Reading the plugs after a normal day's drive will do nothing for you.

If the vehicle is slowing down and the tac shows an increase in engine RPM, i'd assume that the transmission is either changing speeds, or the converter lockup is kicking in/out.

Mgardiner1 wrote:If the vehicle is slowing down and the tac shows an increase in engine RPM, i'd assume that the transmission is either changing speeds, or the converter lockup is kicking in/out.

Hmm Converter lockup sounds like an interesting thing to look into...

Holy crap I have actual input...
This evening I was coasting down a steep hill at 45MPh in 3rd (aw4) I noticed the RPM was modulating between 1000 and 1300 up and down about once per second. I never noticed before but both my 1990 and 1994 Cherokee do it.

I can only guess since it's in decel mode under 2000 RPM it is going into enrichment mode but tossing just a hair too much fuel and ping ponging the revs up and down, since the torque converter was unlocked the surging was only present by looking at the tachometer.

HTH YMMV

I gues that show how anal some of us are... sounds like its fairly normal behavior....

Sir Crusto any updates/add ons to this situation?

Hey Peoples,
Well, I did replace the TPS a couple weeks ago and that made it work MUCH BETTER! New T-Stat, too. Runs right at 195. Still trying to decide if the distributor is set correctly. I did some full throttle runs today, from 45-50 up to about 85. It seems a little ragged, for lack of a better term, around 4000 rpms. It starts great, idles fine, accelerates HARD. Tough to judge. I need a more educated ear to tell for sure. Have a pesky oil leak too. Thought it was pan gasket, replaced that and the cork valve cover gasket. I think it's still leaking. Maybe the rear main. AAAAARRGGHH I HATE oil leaks, or any leaks for that matter. I think I'm gonna' go to the Oregon Dunes this weekend. Do a little mellow runnin' and put some load on the engine. Will report back.

crust1

Hey Jeeers,
Well, things are getting a little annoying. Decided to head to the coast on Sat. Got gas and with about 10 blocks , noticed my Jeep was PINGING Didn't know what to make of it. It's been so smooth and trouble free so far. Thought it might be slightly warmer air temps. Drove to the coast and determined it was pinging mostly under 2/3 to WOT at around 3800-4000. It didn't matter if I was goin' 50, 70, up hill or flat or from a stop. It hasn't done this before. Oddly it seems to be idling a bit smoother. Went to Florence, and as I got there, realized I'd gotten regular gas back in the Valley. Filled back up on Super and went out the sand. I now had about 12 gallons of premium and 8 gallons of regular. Air down, stomp the pedal, SAME PROBLEM So I'm thinkin', my engine either will run on NO LESS than 100% premium, or I'm runnin' lean. I hadn't really done any FULL throttle blasts up to this point. I hosed it down afterward at my family property, a little under the hood included. Check engine light came on afterward. Went on and off on the way home. Now off all together. Just realized now that I probably got water in the temp gauge sending unit. The temp gauge was all over the place on the drive home, (about 90 miles , I was a little worried). I pulled over and no steam, and I could touch the valve cover with bare hand. It was hot, but not overheating. STUPID SENSORS! What's the consensus on the PINGING? Can I turn up the Hesco FPR? They set it at 44 psi. Might it be too low? Move the IAT to a cooler spot? Drive mellow for another 100 miles and go to UniChip. It feel a bit more sluggish in the last week too. Will the dizzy being off cause this problem and /or the ping?

Thanks for your brains peoples,
crust1

Will the dizzy being off cause this problem and /or the ping?
Yes, double check before doing anything else.
John

Hey all,
Here's a little update. I just read an article in Popular Science, I think, on a performance build they did on a new Challenger. They used the Pulsar plugs. I thought it sounded interesting and they're money back guaranteed. Nothin' to lose. I installed them as per their instructions and...MY STROKER RAN LIKE TOTAL CRAP!!! Rough, stumbly, bad idle, felt like dead cylinders. Didn't even leave the driveway. I called their tech line and they said to pull and check each plug and try to figure out which ones "were bad"!!! $25.00 a piece and I got "bad" ones. Three or four of the six looked like they were wet and/or fouled. I put my rc9 Champions back in and it was right back to nice and smooth. I had disconnected the neg. side of the battery as they suggest, "to clear the memory" of the computer. Does this work on an OBDI? Anyway, it ran a little odd after it was back with the Champions. But now it seems to have smoothed out. Why might it have left over effects after the correct plugs were in? Anyway, I have now had a bad experience with these plugs. Anyone else?

T~