High idle, funny shifting, and weird smell?

[gijoecam]

Well, I've got some gremlins that reared their ugly heads this afternoon. I splashed through a couple of puddles on the way home from having dinner at my parents' house this afternoon. None of the puddles were very substantial, just your average snow-melt runoff puddles.... nothing more than an inch or two deep. (OK, the pot-holes may have been 3 or 4, but they don't count)

Accelerating from the last couple of stop signs, I noticed that the transmission didn't seem to be shifting properly. It seemed to be short-shifting, the 1-2 shift was abrupt, not smooth, and the 2-3 shift followed the 1-2 shift almost instantaneously (like it was doing a double-shift), and the 3-4 and 4-OD shifts were also pretty harsh. Pulled the stick, level is good and there's no smell from it.

The second thing I noticed was that it was pulling pretty hard in reverse backing into the garage. Didn't understand why (thought it was wet brakes) until I put it in park and noticed the idle was around 1200-1300. Revs take a long time to come back to idle too (idle being the 1200-1300 range).

The third thing that seemed weird is that I'm getting a funny smell from the exhaust. It smells like when you first put new rotors on, and the first couple times you stop, you are burning the cosmolene off the rotors where you couldn't clean them. I didn't think much of it on Thursday when I got the new muffler put on, but the smell hasn't gone away, and seemed to get worse today when I was letting it idle in the garage. In case it matters, it's a Flowmaster 50 series SUV/Performance muffler.

I'm stumped as to what those three things all have in common? The first two I think may be more closely related.... it almost feels like it did when my Throttle Position Sensor went out on it a while back, but there's no code stored if, in fact, it's bad.

I'm honestly hoping it's just some moisture that got splashed up somewhere it shouldn't have and it'll be all better after she dries out in the garage tonight. Experience with this monster has taught me otherwise...

Any ideas?

-Joe

 

[BradE.]

When's the last time you cleaned the MAF sensor?

 

[gijoecam]

When's the last time you cleaned the MAF sensor?

Never have. Don't plan to. It wouldn't have gone bad just from splashing through the puddles, and a bad MAF should throw a code.

-Joe

 

[BradE.]

A dirty MAF doesn't throw a code, it's not "bad" per se, and it can cause tranny shifting problems like you described.

 

[gijoecam]

Well, some good news and some not so good news.

The good news is that when I left for work this morning, everything had returned to normal. I thought that meant it was just some water from the puddles that worked its way in someplace it shouldn't have.

Then, of course because it's both a full moon AND a Monday, everything was fine until I merged into the freeway. I've got about 5-6 miles to the freeway, so it's usually up to temperature before I merge into traffic, and today was no exception. I accelerated, merged my way over into the fast lane, just as the check gauge light came on... the temp was near the top of the normal range and climbing quickly. Off to the shoulder I go. I no sooner put it in park than the temperature guage starts coming back down, so I thought that was a good sign. Pop the hood, let it idle for 30 seconds or so, and she's back down to just a hair above where she normally runs, no signs of overheating... no boiling over, no vapors, no oil in the antifreeze indicating a head gasket.... no clue.

As soon as I attempted to merge back into the freeway, same thing.... climbing temps. If I kept it under 60, it would stay in the normal range... a little higher than normal, but in the normal range none the less.

So, I double-nickled it the remaining 30 miles to work, and things seemed to be ok.... light mist on the roads just from the leftover melting snow from this weekend. In the 5 miles between the freeway and work, the temp hovered just above where it normally does. I don't need to go over 35 at that point, so it never really moved higher (or at least not that I noticed). Then, when I accelerated after exiting the freeway, the shifting problems returned. Short-shifting, almost no second gear as it shifted to third almost immediately. Idle around 1200 (1000 in drive).

Got to work, and again checked for anything obvious..... nada. Trans fluid smells fine and is pink, not brown, no oil in the coolant, levels are all good....

I'm pretty sure moisture got to something, but what? I could see the MAF causing a high idle and/or the shifting problems, but overheating? Simply a coincidence with a bad thermostat? The overheating is classic stuck thermostat, but the shifting/idle issue is still a mystery to me. The high idle alone would make me think the IAC is schticking, but coupled with the shifting...... I'm not sure on this one.

Oh, and since I forgot to mention it, it's a '98 Sport 4.0 SOHC, coming up on 89k miles.

-Joe

 

[gijoecam]

Ran out at lunch... Started fine, everything was kosher. No idea what the deal is here.

Scanned the codes just for the heck of it and came up with a P0442 Small Evap Emissions leak, which could certainly explain the high idle. Gas cap was tight (although I filled up Saturday Night before all this started, so I thought this might be the culprit... no dice), there were no obvious vacuum leaks under the hood, and it was running fine, so I decided to see if I could find a thermostat for it.

On the drive up to Murrays, I managed to get halfway there before the temp started to climb. A soon as the temp got up above 2/3 through the normal range, the funny shifting and high idle returned. Certainly sounds like a vacuum leak that only occurs when something happens, but can a small vacuum leak cause overheating and funny shifting? I'm so corn-fused right now....

-Joe

 

[gijoecam]

More good and bad.... I put 2 and 2 together and it dawned on me that yesterday when I first had the problem, I popped the hood and noticed the evap test hose (with the green cap on the connector) was rubbing on the AC compressor. It didn't look bad, so I tucked it up out of the way. Apparently the bumps had jarred it loose from wherever it was supposed to be clipped originally. Upon closer inspection this afternoon, it had rubbed through. I guess that explains the small leak in the Evap system. Taped it up and it appears to be OK.

Started it up, and it idled fine. Took off down the street and the first series of shifts were fine. Stopped, and as the temp climbed, the second set of shifts was harsh and premature again, and the temp climbed way up to the top of the normal range again. Checked the tranny fluid, and again, it appears to be fine. No brown color, no burnt smell.

Could still be the t'stat, but would an overheat condition cause a weird shift pattern from the transmission?

-Joe

edit: Not sure why I can't post a reply, but I fixed it.

Amazingly my solution involved a $30 thermostat and gasket from the dealership, a piece of electrical tape, and a zip tie.

I used the electrical tape to fix the Evap emissions hose slow leak as mentioned above. I then used the zip tie to attach it to the battery tray.

On a long-shot, I swapped out the thermostat. I figured that since it was only $30 and 3 screws, it was worth a shot, and wasn't going to hurt anything with 88k on it anyways, it was probably due. Started her up, let it come up to temp and burped the system, and took it out for a ride, gentle at first just in case. After managing to make it to the end of the street without the gauge moving, I went WOT at least 6 times with no problems. The temp gauge never moved, the idle stayed right where it was supposed to, and the shifting was smooth as butter once again. I guess I got lucky.

Now, if I could just figure out a way to use duct tape to fix the shocks......

-Joe

 

[ExplorerDMB]

I do not like the signs of your "weird smell" and gauge problems. It reminds me of a van I had to test drive and it started to over heat, then it would go back down, then back up, then back down. Pulled the heads, cylinder heads were cleaned. Antifreeze had leaked into the cylinders. You may need new head gaskets. Good luck

-Drew