Civic VX Throttle Body trouble. Used replacement is also BAD. Any way to fix?
 

Throttle body on my 92 Civic VX is causing the car to rev up and down at idle (800-1200 rpm). I know it's the throttle body because I also have a 94 Civic. Swapping throttle bodies made the 94 Civic idle poorly and fixed the idle on the 92 civic. I checked that it's not the MAP sensor by swapping MAP sensors.

I ordered a used throttle body from A and A Auto Truck Salvage USA-KS(Wichita) 1-800-566-9572 a couple months ago . I'd advise against dealing with this guys - very rude and just plain bad at delivering anything but excuses. This guys at A and A Auto Truck Salvage send out a wrong part and after a months and 20 or so phone calls and hearing just as many excuses I never got the correct replacement. Last time I called they claimed they never took my order! Now I got a refund, but only for the part, they did not refund the shipping WTF. Worst experience.

So this week I ordered a throttle body from another place and got it delivered yesterday. I cleaned it up with mineral spirits and put that TB in. This replacement TB it's also causing rough idle. Is it bad?

Any way to fix the throttle body it? At this point I'd rather try and fix it, as a new replacement is ~$500 and I'm tired of dealing with junk yards.

I heard that the throttle shaft could cause vacuum leak - is there a gasket that could be replaced? Anything else that could go wrong with it?

You sure it's not the idle air control valve? Usually that is what causes an unstable idle, not the throttle body.. It could also be the Fast Idle Throttle Valve as well.

https://www.team-integra.net/sections...ArticleID=1174

On anything other than Hondas I'd be thinking of fingering the IAC as well.

Hey, yes I'm sure the problem is within throttle body because bad symptoms follow the bad throttle body when swapping between the two vehicles. Both vehicles work fine with the "good" throttle body

Over the last couple years I've checked all the emission/intake/ignition/fuel components and hoses on both vehicles (IACV, EGR, PCV, injectors, O2, plugs etc etc) by swapping components between my 2 vehicles and also with a spare engine. The IACV is fine. There is no fast idle valve on VX.

throttle position sensor, check it. It should read 0.50v at idle.

That's the lines I was thinkin' along...

Can I check if TPS is causing the idle problems by just disconnecting the sensor?
I don't like taping in to the wiring/backprobing connectors, as that damages connector seals and could cause more trouble down the road

Also has anybody tried disassembling the throtte body? Are there any gaskets that could be replaced?
I fixed my other throttle body by replacing o-ring under the map sensor. On my other car that little o-ring was letting in enough air to cause fluctuating idle problems till i got it replaced. Now it's rock solid. I checked the map sensor o-ring, but there are probably some other seals also around TPS sensor and throttle plate shaft, but I can't find anything about it either in the manual nor online.

Thanks

That's not how you check devices... What you do is you disconnect the TPS, get a multimeter, use the probes on the connector and see if it's giving a read in a valid range.

Yes, I can check the resistance by disconnecting the wiring.

socalsupehero suggested to check the voltage at idle - for that the wiring needs to be connected, so I'd have to backprobe the connector

Yeah, it has to be connected. I just probed the wires from the backside of the connector. No need to get too crazy with it. I had the same problem after my swap, tried out a bunch of different things before this. TPS sensor was waaaay off.