Pulsating Idle

[Tatohead]

Hello, Noob here.

Purchased a 90 Camry 4-cyl 5-speed yesterday. Car is driveable, but once it comes off high idle after warm up, the idle "pulses". Almost like a slow heartbeat. Throttle plate steady.

Any ideas on where to start?

Thanks, hope to enjoy the forum and contribute often.

[Mike Gerber]

I would start by cleaning the throttle body and the idle air control valve. Here's a DIY on the later 5SFE engine. Your 3SFE engine should be almost identical:

How to: Cleaning Throttle Body -4 Cylinder Engines- With Pictures

If that doesn't help, I would then start checking/replacing the ignition system components. Plugs, plug wires, distributor cap and rotor. If that doesn't help, I would then check the coil inside the distributor. To do that you will need a digital volt/ohmeter and the spces from any manual. If you don't have a manual you can download one for free at the top of the Camry forum over at AutomotiveForums.com. Here's the link to those manuals:

http://www.automotiveforums.com/vbul...d.php?t=497839

I would also remove the coil and inspect it carefully for cracks. That's a known trouble area on these cars as they rack up lot's of miles.

Mike

[typesix]

Also check for cracked vacuum hoses or loose ones. Mine had that problem due to vacuum leak.

[Tatohead]

Got it solved today. I picked a full throttle body at the JY from a 91 Camry. Turns out the TPS on the donor was completely different (donor car had cruise control; perhaps that's why it was different). I couldn't just use the new TPS because the plug was also completely different.

So, I just swapped the IAC from the donor to my throttle body. I washed down everything really well with TB cleaner. The hardest part of the whole job was the rubber gasket to the IAC unit. It's larger than the space it's filling!

Idle steady!

[hairball]

My 90 Camry DX (with A/T and cruise control) has the SAME issue! And I've checked every vacuum hose and and the entire engine for a vacuum leak and found nothing. I did find that a couple of my hoses are not routed correctly, (see pic) but tried switching them around and it made no difference. The #2 vacuum hose wasn't attached to anything at all, but had NO leak. Odd. This is from my engine:


This is a picture I took of a low-mileage 90 Camry with same engine and transmission (so I assumed hoses were routed right)...


But the one thing that seemed to check out by tests I was informed to do was the TPS. It seemed to pass all tests. BUT, this doesn't mean it is NOT defective or acting up. So thanks to your posts, I'm going to run get another one today and see if my problem is solved.

I know what you mean about how annoying it is when you let off the gas and the idle pulsates. I've been baffled by it for 14 months that I've had this car.

Thanks for sharing your tips!

[Tatohead]

Golf tee!!! LOL!

I guess if it works, it works....

[hairball]

I've used them for 30+ years to plug vacuum lines when I disconnect them, but this time I thought I had a vacuum leak so I shoved that one in that line because the line was not hooked up. It didn't help. But yes, the Golf Tee is a mechanic's best friend sometimes!

[Doctor J]

Check your EGR vacuum modulator and vacuum ported switch!

[hairball]

Thanks! I'll do that today!