Oil Change: Now won't idle???

[trscott]

Okay, this is really weird. I took my '91 FJ80 in for an oil change to the local quick service shop and when I drove it away it suddenly wouldn't idle. Every time I let my foot off the gas it stumbles for a second or two at 200 or 300 rpm and then dies. The only way to drive it at all is keeping my right foot on the gas pedal. It was perfect when I took it in, very smooth idle at 700 rpm or so. At cruise speeds it seems fine, maybe very slightly rougher, but certainly driveable.

I have looked and looked at every hose and wire and I can't find anything obviously disconnected.

What am I missing? I assume it has something to do with something the technician did while changing the oil and air filters, damaging a wire connector, breaking a hose, etc., but I just can't find anything wrong.

I am ruling out anything more serious because it was perfect before the oil change and awful after, too much of a coincidence.

Thanks!

 

[MLX450]

I've always heard horror stories from "quick oil change places".

Check the intake hose for cracks and also check if your oil cap is tight.

 

[ToothDr]

I've always heard horror stories from "quick oil change places".

Check the intake hose for cracks and also check if your oil cap is tight.

Yeah, stay away from the jiffy lubes of the world. I took a 92 toyota pick up in once for a diff drain and fill. They drained the diff but forgot to fill it, idiots.

Like MLX450 said, take a good look at the air intake hose for small cracks, especially on the underside of the hose. A cracked hose can allow unmetered air in. This can affect the idle. If they bumped it they may have opened up cracks already present.
Also look for any loose wires, grounds etc.

 

[sdnative]

Check the intake hose for cracks

x3... The big one that goes from the air box to the intake manifold.

 

[jonheld]

Make sure the dipstick and filler cap are tight. You have a vacuum leak or the intake hose is split. The dipstick has a gasket and so does the filler cap.

 

[trscott]

Good call! Thanks!

Good call guys. It was a gaping crack in the bottom of that pleated intake tube. Freezing weather, and an over-aggressive technician yanking to get the air-cleaner lid off probably did it in. It had nearly separated completely, but I couldn't see the crack on the bottom hidden in the pleats till I took the air cleaner lid off again.

Despite 28 degree air, I managed to get the outside of the tube cleaned up with some denatured alcohol and then wrapped it with three wraps of duct tape for a temporary patch and sure enough, that fixed it. Starts and idles fine now.

I first tried to get the tube off, but everything is so stiff in the cold that I am afraid I will break something else. I don't have a heated space to work on it. It seemed like the end farthest from the intake manifold might be glued to the piece it is clamped to. Even when I had the clamp completely loose, I couldn't budge that end free. The end attached to the manifold was loose enough to slip around a bit. Hopefully the duct tape will hold till I can get a replacement. Probably not something Napa or Autozone are going to stock.

Thanks very much for your help!

 

[cruiserdan]

Have the shop buy you a new hose...

 

[Elijah]

The intake tube is also hard and brittle from almost 20 years of service, it's normal for it to be that way. Best price on the new one will come from cruiserdan, who's on this forum.

edit. He's the one that just replied ahead of me