2001 Expy new problem

[JamaicaJoe]

My 2001 Expy 97K Miles has been sitting idle for quite a while, about 15 months with a run up every couple months. This week I decided to get it ready to sell so I went to start it and it seemed to be misfiring. I was not surprised because it has been raining and very damp. The thing is, it has a ton of pep and just seems to stutter when above 1100 to 1500 RPM. The Check Engine Light is not illuminated and I scanned for Mode 06 and there are no misfires being tallied up. Weird, because I usually expect that, and then shut it down and let it dry out (wet fouled plugs), but it is not doing that, it is not the usual misfire with awful bucking. Nope, it is stuttering under load and no codes. So I was reminded that the MAF sensor could need cleaning. That made sense so I bought some MAF Cleaner (CRC) and cleaned the MAF in-situ. It is a ***** to unplug the cable so, yeah I put paper towels under the inlet cone and sprayed away front sides and rear. No improvement whatsoever. I pulled the connector to the IAC Solenoid and the idle dropped way back so I assume it is not the problem.

I should note that bad fuel was a consideration so I added 6 gallons to the existing 5 gallons and threw in some HEET. It seems it was running just fine a few weeks ago, so odd that the fuel would go bad very quickly. The fuel pump was changed about 12K miles back. No hard starting, primes quickly.

Any troubleshooting thoughts for tomorrow afternoon? I really want to get this girl sorted out so I can sell it.

 

[jr1under]

Any troubleshooting thoughts for tomorrow afternoon? I really want to get this girl sorted out so I can sell it.

Could there be a faulty ignition coil? That definitely will cause misfires, bucking, shuddering and a strong desire to borrow your wife's car. Usually a failed coil throws a P030x code but not always and it's that 'not always' instance I'm referring to.

This is a long shot but I have experienced it a few times and it's an easy problem to fix.

 

[JamaicaJoe]

Could there be a faulty ignition coil? That definitely will cause misfires, bucking, shuddering and a strong desire to borrow your wife's car. Usually a failed coil throws a P030x code but not always and it's that 'not always' instance I'm referring to.

This is a long shot but I have experienced it a few times and it's an easy problem to fix.

I have no codes at all. Mode06 shows no individual misfires on any cylinder. It is as if the ECU thinks everything is fine.

 

[jr1under]

The possibility I'm talking about is having a bad coil w/ associated symptoms but no code. I only brought it up because it has happened to my 1999.

 

[Billme]

How long are you running the engine? Are you driving it at least enough time for everything to come up to operating temperature?
Shuttering can also be transmission associated..

 

[JamaicaJoe]

How long are you running the engine? Are you driving it at least enough time for everything to come up to operating temperature?
Shuttering can also be transmission associated..

Yeah I am running it up to temp. It shows Closed Loop . I hope to simulate open loop by unplugging the MAF to see if it idles OK. Yesterday I cleaned the MAF with the CRC product to no avail. It is impossible to unplug the MAF when inside the "funnel". I will try again to remove the harness that is under the air cleaner where it bolts to a shelf. I think I cleaned it well, just not the plug connections. I should mention that the hot wire in the MAF appears to my terrible eyes to have a sort of white oxide appearance, even after cleaning. Is this normal?

 

[JamaicaJoe]

The possibility I'm talking about is having a bad coil w/ associated symptoms but no code. I only brought it up because it has happened to my 1999.

I have owned this vehicle since about 20K miles in warranty. It has always been sensitive to dampness under the hood and has had , under warranty 3 coils and plugs replaced. At about 45K miles I had all the plugs changed by dealer (very expensive). I kept the plugs and the gaps very wide at 45K. So much for 100k plug life. The dealer did not change the boots from what I can tell and as the miles piled up I have had intermittent misfire events that I trapped in Mode 06 using my Scanguage II. When it got bad, I replaced a coil and boot, or the boot at minimum. The incidents were infrequent and except for the aforementioned repairs, never set CEL or a code. I just kept an eye on them. But strangely this time, there are no Mode 06 misfires being tallied. It is as if the ECU thinks everything is just dandy while I have a stumble 1100-1800 RPM under load also at idle, a sort of stumble here and there. I am thinking it is in a sensor or something affecting fuel trim . I don't have a "real" code reader so just hoping to outfox the gremlin.

 

[JamaicaJoe]

How long are you running the engine? Are you driving it at least enough time for everything to come up to operating temperature?
Shuttering can also be transmission associated..

It seems to be shifting fine, though I am being careful not to subject too much strain on the transmission until I sort this out. I probably should mention the almost 3 year old battery is not in its best shape (drained repeatedly in storage) but has been cranking just fine.

 

[Fastcar]

Spray the wires with WD40.

 

[k4vbb]

My best guess based on what I've read so far is that you have a vacuum leak somewhere. If you can, check your long-term fuel trims and see if it's running lean. If it is then you'll know where to start looking.

There are multiple reasons why an engine would run lean, but vacuum leaks are probably the most basic.

 

[Splicer1998]

My 2001 Expy 97K Miles has been sitting idle for quite a while, about 15 months ......

I should note that bad fuel was a consideration so I added 6 gallons to the existing 5 gallons and threw in some HEET. It seems it was running just fine a few weeks ago, so odd that the fuel would go bad very quickly.

..... I don't have a "real" code reader so just hoping to outfox the gremlin.

Fuel starts to degrade after 30 days, and yours is over a year old. If you suspect it's bad (it is) you're better off pumping it out of the tank first. Putting in fresh gas and some additive isn't going to magically bring that stale ass fuel back to life, it's just going to make things worse. Look at it like this: If you have a half gallon of spoiled milk in your refrigerator, would you add a 1/2 gallon of fresh stuff to it then pour it on your cereal? Your stomach wouldn't like it at all- same goes with your engine and that stale/fresh fuel mix you have in there.
Also, without proper troubleshooting you are just spinning your wheels and wasting time. Any chain auto parts store can read codes for free if you don't have a "real" code reader. (FWIW I've had many coil packs go bad over the years on several 5.4's that didn't throw a code)

 

[JamaicaJoe]

Today I removed the air filter housing and MAF cone entirely. Gave the MAF another CRC-MAF cleaning as well as the mating connectors at the MAF and vehicle harness with CRC-Electrical cleaner.

Then I tested at idle with the MAF connected and disconnected. I could not discern any difference with the idle, which actually does not seem too bad. However under load without the MAF the engine really bogs down. I had expected it to simply operate open loop and be driveable without the MAF.

I banged on the MAF housing a bit to see if a loose connection. I ran propane gas around the various vacuum and manifold connections and heard no change at idle. I also turned off over drive because someone mentioned a transmission interaction. No change. It is certainly bad under load, but there is a stumble in the power band above 1100 RPM. I don't think it is a torque converter problem as in neutral I can feel the problem. ATF fluid was changed about 30K miles ago.

Bad fuel? as I said I added enough new gas to dilute the old and added some Heet (red). The stumble is same, so if bad fuel maybe the injectors are logged up. I don't have any other suspicions like coolant leaks. The exhaust seems clean, but there is a bit of chuffing at idle. I don''t know if it always did that or its just those 4 strokes..

I am tempted to drive it like this for a few dozen miles to see if anything clears up. However I dont want to stress the transmission. We are on flat ground here so there is that.

 

[neilh]

A good enough code reader is like $15 bucks on amazon....You can spend more on sprays and cleaners than that..... https://www.amazon.com/MOTOPOWER-MP...8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

 

[robsant]

This may sound crazy, but I had a similar problem a while back. I thought it was the transmission. I actually took it to a transmission specialist and he just put in some transmission liquid. Said I should observe it for a few days. I also had a tire that needed air. So, I took it to a tire shop. After putting air in the tire, he said that I should replace a tire (not the one he had just filled up). I asked why and he said the tire was deformed. Luckily he had the same tire for sale. I replaced it and what I thought was a transmission problem was fixed.

 

[JamaicaJoe]

Thanks that

A good enough code reader is like $15 bucks on amazon....You can spend more on sprays and cleaners than that..... https://www.amazon.com/MOTOPOWER-MP69033-Universal-Diagnostic-Protocol/dp/B07Z3HB7DR/ref=sr_1_1_sspa?crid=3SLHDPEWL02Y5&dib=eyJ2IjoiMSJ9.pSqtNFRp_gGHvSVaqQ-CynbqXEX6BZMeOqob3T9fXyIH71KAgWiuEiS77LwSaZzGDhetynjf8pHsHcbNnvgPk03_uXtksypZF95KWa37DByeWmV429boR7dcbTVP4fbYt7dsXRwtpRkpdMXT4QK739TXQiCEu4mm2bCM0RNnL8x-ebf8TQ0CO9cRPW8i9RnwUQTE9OkY5qkqfjFa1e23QNfNV7n3Wc2jwknWn8XHM0nk4bwr8Yf-whL47I4hL0n5kjJGL-Ev2XisygFO6S44hSUn7lSwUNyhzpwLM8H2VQ0.y_NVerYJpPMDmu6kqMe76L7ax7ucHXdCJ-BNO_962Og&dib_tag=se&keywords=obd+scanner&qid=1756740910&sprefix=obd+,aps,544&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

Thanks, that is a good deal.

 

[JamaicaJoe]

This may sound crazy, but I had a similar problem a while back. I thought it was the transmission. I actually took it to a transmission specialist and he just put in some transmission liquid. Said I should observe it for a few days. I also had a tire that needed air. So, I took it to a tire shop. After putting air in the tire, he said that I should replace a tire (not the one he had just filled up). I asked why and he said the tire was deformed. Luckily he had the same tire for sale. I replaced it and what I thought was a transmission problem was fixed.

Tires get flat spots if parked too long. I use chalk to mark where the tire meets the driveway and then try to repark it differently. My problem happens parked, in park, or in gear under load. Not too concerned with drivetrain issues.

 

[JamaicaJoe]

Ok; still trying to sort out this problem. I suspected that the battery could be the culplrit as it is getting bad. So I have a marine battery that is good and I jumped it to the vehicle battery after charging it. I did give the vehicle battery a bit of a top off. I first disconnected the vehicle battery for an hour and shorted the cables together to clear ECU memory. Initially the idle and quick throttle blips sounded so sweet I though I fixed it. but soon it was back stumbling off throttle. Probably coinciding with being closed loop. Now I am wondering about the throttle position sensor. I selected TPS on my scanguage and it seemed the numbers were jumpy and restricted range 28-32 units ???. I should have tried it key on engine off. Maybe tomorrow. I did try to have the ECU relearn the TPS sensor from instructions on line that may be wrong. TPS could that be doing this? Again, no codes no CEL, No Mode#06 misfires, just bad driveability.

 

[jr1under]

No Mode#06 misfires, just bad driveability.

Are there any other Mode 6 readings that are out of normal?

 

[JamaicaJoe]

Are there any other Mode 6 readings that are out of normal?

I am using a Scanguage II which is primarily a hyper-miler tool. It will read out a lot of parameters and codes and PID's , but you have to write script for it to pull out specific Mode%06 data. Because of past COP and plug problems I have it focused on misfire codes, for which none are coming up. I have no CEL either. It just runs crappy off idle especially under load. But I can hear it stumble when in park so it is not the transmission.

 

[JamaicaJoe]

Gonna test the TPS voltages in-situ. It seems I could waste hours with stuck bolts firing the parts cannon at the TPS.