Car dies when letting off the gas. What is really going on?

Maintenance/Repairs
1

I have read some of the discussions here, and I have googled other discussions about it on other forums, but it didn’t seem like there was a definitive solution or answer to the situations that were most similar to mine. I wish people would post back the outcome if they get their problems solved or not.

I have a 1999 Camry. I just spent $1250 (half of it borrowed) to have some basic maintenance, diagnosis, and serious repair work done. More than half of the serious (translate: expensive) work involved replacing a charcoal canister and installing a thermostat. The check engine light had been on for at least 10 years. And I had a gas pumping problem by way of the pump shutting off after only pumping a few cents worth of gas. Needless to say it was a royal PIA to fuel up my car. As far as the check engine light, a friend would clear the code so I could have it inspected.

Then more than 2 years a shop took out my thermostat because a hose had sprung a leak and they rigged up a temporary hose until they could order the part. I never went back because I couldn’t afford it. I know it wouldn’t have been a terribly expensive repair, but at the time it was more than I could afford. So for almost 3 years I have driven with out a thermostat and also couldn’t get it inspected.

Fortunately I was finally able to get the necessary repair on my car–replacing the charcoal canister and thermostat–so that it could be inspected. I picked the car up yesterday and everything felt fine and the car ran fine.

Today I drove it about 12 miles from my home, made 3 back-to-back errand stops of not more than 15-20 minutes each and everything seemed fine. Nothing felt or sounded out of the ordinary. Then when I was leaving my 3rd stop, the car would not start unless I gave it gas. And it wouldn’t stay started unless I gave it gas. In other words, the car would go, but as soon as I would take my foot off the gas to press the brake to put it in gear, the engine would die. There was no problem restarting it as long as I gave it gas, but I could not let off the accelerator at all or it would immediately die. The car would go just fine, but if I let off the gas for any reason, even if I was driving 40 miles an hour on the street and let up completely off on the accelerator, the rpms would immediately drop to 0 and the engine would immediately die—no noise, no shuttering, no nothing—just die. This problem occured almost the whole 12 miles back to my home. Then when I got about a mile and a half away, it went back to behaving completely normal and did not die when I let off the gas.

Of course, I will check back with the repair shop, but I would really appreciate some advice and a bit of a heads up on the potential problem and cost. I don’t have much left to work with and this problem is significantly dangerous for the distance I have to drive to work each day.

Sorry this is such a long post. Thanks!

2

It sounds like it could be a bad idle air control valve (IACV). Apparently your year Camry is known for faulty IACV’s:

Call your local dealership and ask of there is a tech service bulletin (TSB) on the IACV. If so, you might be able to get a free one from the dealer. If not, have your mechanic check the IACV and clean or replace it if necessary.

It could also be as simple as cleaning the throttle body.

3

It sounds like your idle air control valve (IACV) has given up the ghost - or its wiring has a problem that is leaving it with no power. You “gas pedal” is really an “air pedal” - it just opens the throttle plate and lets in more air. The computer “sees” this through sensors and delivers the gas. The IACV is what handles the air when your foot is not on the “air pedal.”

The wiring and it’s power supply (from the engine’s computer) needs to be checked. If that checks out then you probably need a new one, although sometimes a cleaning can do it as the ports can get all clogged up. This should not be a terribly expensive thing.

4

I appreciate the responses, which indicate the same probable cause as most of the other forums I’ve read. Appreciate, also, the link to the article. However, the article says this problem is more of an issue during cold starts, and that was definitely not the case with my car yesterday. In fact, nothing like this has ever happened before. The engine is not the original engine, which was replaced in 2009 with a new “after-market” engine (I guess that’s the right term). In other words, the original engine was not rebuilt, and I did not get an engine from a salvage yard. So even if Toyota had a service bulletin, I doubt my IACV would qualify for replacement by them. For the record, I never had this problem with the original engine either, which had over 165,000 miles on it in the end. At the present time, I barely put 10,000 miles each year on my car. For several years I did use cheap gas, but now I use a name brand gas, and for the past several years I’ve also poured in a can of SeaFoam every 3-4 months to try to clean things up a bit.

I will be contacting the shop where I took it last week and post back what the outcome is. Thanks so much!

5

An IACV problem doesn’t need to be connected to hot or cold - although it could be sometimes. It’s also not an integral part of the engine. It’s a peripheral part. So it’s probably the same IAC that was on your original engine, and having had a rebuilt engine dropped into the car is pretty much irrelevant.

By analogy, it’s sort of like getting a new lamp in your house to replace one that broke. The new lamp won’t come with a light bulb. You will take the light bulb from your broken lamp and then put it in the new one. Then if the bulb later blows out, it has nothing to do with the new lamp. It’s just that sometimes light bulbs blow out.

6

Thanks for the explanation. Well, it hasn’t happened again, so I haven’t called anyone about it. And truthfully, trying to get time off from work, plus arranging alternate transportation to take my car to the shop is a big hassle. So I guess until I have more of an issue with it, I’ll just let it go for the time being. But I will definitely mention this if and when the time comes. Thanks again!

7

Since it hasn’t happened again, if it does first assume something like a loose/damaged wire that intermittently jiggles the wrong way. It’s not that the IAC motor itself can’t get randomly wonky, but if its that intermittent I’d suspect a wiring issue first. Of course, that kind of thing tends to be very cheap to fix - but often costly to find in terms of labor time.

8

Other than agreeing with cigroller about this appearing to be an IAC problem I might add something about SeaFoam. SeaFoam is a great product first off and adding it to the fuel tank can help clear things up in the fuel lines, fuel injectors, and also by helping to remove deposits from behind the heads of the intake valves in the cylinder head

SeaFoam in the fuel tank will not clean up the throttle body or IAC though as SF does not pass through that area on a running engine. Only air passes through that area.
Cleaning the throttle body and IAC would involve feeding SeaFoam into the intake tract above the throttle plate or by removing the throttle body or IAC and cleaning it manually.

9

I think the recent repairs, something didn’t get quite put back together correctly. Maybe a connector is loose. Ask your mechanic to check the connector for the throttle position sensor and the connector for the IAC. If the engine coolant temp sensor connector was loose, that would cause this symptom, but would almost certainly turn on the CEL. Is the CEL on now? It might be worth it to have the diagnostic trouble codes read out even if the CEL isn’t on. Not every problem registered as a DTC turns on the CEL. Did the new canister solve the fueling problem?

10

I agree with the others who say it sounds exactly like your IAC.

If you don’t want to buy a new IAC, you can remove and clean it, and it will work like new. I’ve cleaned IACs for that year Toyota without any problems.

11

Stalling problems should begin with cleaning of the throttle body. Since the repair of the vapor canister the fuel system has had to adjust and you may now need more minimum air bypassing the throttle plate than you did before.

12

I have a 1985 chevy and it has a 1987 305 or 350 tbi i just replaced the iac valve but everytime i come to a stop it will stall while it is in gear so i have to put it in neutral so it wont stall thx

13

Your welcome. And your punctuation kit is being sent.