Anyone else having repeated throttle body failures?

[Eaton PSI]

I had a throttle body fail in january of this year. Yesterday the new one started to glitch just like the old one.

Erratic idle and cruise, and engine revs increasing to 2k-3k when pushing the clutch in with no input on throttle pedal. Cycling the throttle with the engine off, it sounds squeaky and unhappy.

The car has a harrop supercharger and the throttle body is rotated 90deg (black plastic cover faces upwards).

The last one behaved like this intermittently for a few weeks before I finally got stuck in limp mode.

Anyone else having throttle body issues?

[ArCha]

I've had similar, also on a Harrop. A few months ago I got stuck in limp mode as well, very annoying since there was no code until then. We noticed a voltage change when jiggling the jumper harness to the throttle but pulling the harness and doing a continuity check revealed no issues and we couldn't repeat the finding after we'd reassembled either. Tried cleaning the throttle body and MAF, no change.

We ended up swapping one of the relays and that seems to have resolved everything but I don't drive the car very often to be definitive. This was the same day as trying some of the other fixes. Just turned off the car, swapped a relay and when it turned back on the problem was gone.

[Eaton PSI]

Yes, same here. No codes, just odd behaviour until it eventually goes into limp mode. Fortunately I keep an OBD dongle in the car so I was able to reset it and get home.
Some days it does it on the way home from work. It will start up fine in the morning and not glitch for another week.
I pulled an old throttle body apart and checked the motor on 12v. It sounds ok when horizontal but a bit odd in the vertical position. I wonder if the harrop throttle body relocation causes issues.
The gears were all completely dry, no trace of grease or anything. The shaft for the little idler gear actually had a tiny bit of rust on it.

[Muskoka800]

Sounds like a Harrop problem.
I have had zero such issues running Edelbrock for several years now.
Perhaps Harrop have a solution???

[Eaton PSI]

Is the throttle body rotated on the edelbrock?

[Muskoka800]

I’m thinking no but can confirm later today. The alternator was the only component I recall needing re-orientation during the kits install. The kit did include new, longer hoses for the TB coolant supply/return.

[Eaton PSI]

I daily drive mine, around 35,000kms with the harrop on it.

[Muskoka800]

Have you reviewed the posts in the Harrop owners forum under the Forced induction category?
There’s not much activity in these forums of late but likely some good historical info to be found there.
Good luck!

[menikmati]

Originally Posted by Eaton PSI

Is the throttle body rotated on the edelbrock?

The throttle body is rotated the same on the Edelbrock, 90 degrees CCW from the original position with the black plastic housing pointing upwards.

[Eaton PSI]

When I get a chance I will open up the electric motor from my original bad throttle and see if there's anything interesting in there...

[Muskoka800]

Originally Posted by menikmati

The throttle body is rotated the same on the Edelbrock, 90 degrees CCW from the original position with the black plastic housing pointing upwards.

I stand corrected. That said, no TB issues here after years of enjoyment.

[Eaton PSI]

So I opened up the electric motor from the throttle body that had a history of codes and limp mode. It all appears to be good. I'm pretty familiar with brushed motors as I am a lifetime RC nerd. Nothing wrong with this one. Weird. Maybe the sensor goes bad.
I had to destroy it to get it open so there's no fixing it even if there was something bad in there.

[Eaton PSI]

It probably won't make any difference but it was easy to do...
Ball bearings fitted to the idler gear in the throttle body. This throttle was making a squeaking noise. When I opened it up there was no trace of any lubricant anywhere and the shaft for the idler was rusty.

[Eaton PSI]

Today limp mode struck again! Throttle body #2 failed.

I had some spare time so I did some testing. I put my original bad throttle back on, still has same problem. I had already swapped the motor inside this throttle.
I removed the plastic cover plate from bad throttle #2 and fit that to bad throttle #1. Now throttle #1 has same issues as throttle #2.
Then I fit the plastic cover from another previously untested throttle (bought from water damaged car at wreckers) to throttle #1 and its all good!

It appears that the position sensor in the plastic cover is prone to failure. The throttles are made by nippon denso and I think variants of it are very common on many cars, subaru and others. I'm going to head back to the wreckers and get some more cover plates from similar throttles and see if I can fix my other bad one.