memsiej

Yesterday I cleaned my IAC and replaced my TPS. I STARTED to work on the valve cover gasket but didn't have the right socket.
Drove my 92 (automatic) to work this morning and going uphill I noticed a high pitched noise, only when accelerating. Kind of like a whistling/grinding maybe? It stopped when I took my foot off the gas. Up the really big hill, however, towards the top it felt like I was losing power. Like I was foot fully on the gas but was decreasing in speed. What happened? What could this be? Did I mess up putting anything back together with the system I was working on? Hoping to get some leads before I leave work today so I know whether to take it to the shop near here or take it home to work on.

Thanks!

memsiej

This vacuum hose (?) seems loose, and the next one has a tiny crack in it. (Not the phosot of my actual jeep, photo stolen from the internet).

GreaseMonkey17

Typically a high pitched whistling is a intake manifold leak . Try shooting brake clean around the intake manifold at idle and see if the rpm's pick up at some point that would indicate a intake manifold leak . That's the direction I'd be heading but I have not heard your particular sound either .

memsiej

Thanks for the response. Noob question- what/where is that? Want to make sure I'm not spraying stuff randomly under the hood?

GreaseMonkey17

Right under your red arrow is the intake manifold. I would suspect the lead right up next to engine .

memsiej

In the first photo? Possible that I messed with this when I was working on it yesterday? Or coincidental timing of that failing?

GreaseMonkey17

That I can't answer unless vehicle was in front of me . I'm sure you've checked everything you touched yesterday to be sure it's not the cause . Coincidence would be my guess if not a mistake from your recent work .

jordan96xj

There is a vacuum line that runs from the intake manifold over to the brake booster canister. They are known to whistle when they are leaking. The brake booster is the large black cylinder directly in front of the driver, right under and behind the brake fluid reservoir. Its in a prime location to have been knocked around during a throttle body/IAC job. Is it possible that got bumped when doing your work?

memsiej

Thanks!! I'll take a look in a minute here. Other thought is that when I ripped apart the TB I noticed there was no gasket between the throttle body and the manifold. Could this be an issue?

**EDIT just checked, that hose is totally in place. Was a good idea though.

GreaseMonkey17

Yes there should be a gasket

jordan96xj

That gasket missing is likely the cause of the problem. It would explain why it is happening under heavy acceleration/load. At some point the motor is able to pull air easier through the unsealed base of the throttle body then through the air filter. You were probably getting away with it before the throttle body job, but now it is rearing its ugly head.

The problem with air sneaking in where the gasket would be is that is the air isn't being measured by the MAP sensor, so the computer starts trimming the fuel to adjust for what it thinks is less air coming through the throttle body. This will pretty quickly start to rob power from the motor as it leans the mixture quickly.

memsiej

Just went and picked one up and took the throttle body apart to slap on the gasket. Low and behold, on the top there was half a flattened ****ty gasket, and on the bottom the other half of a flattened ****ty gasket. Peeled that on and replaced it, SO FAR it seems to be running much better but I havent tested the real hills yet.

Now thinking that I didn't notice the gasket the first time around, ripping up the TB split it in half, and then there was a crack in it when I put it back together. Here's to hoping that's all it was!

EZEARL

Couldn't have been good.

GreaseMonkey17

Good to hear !! That should be it

jordan96xj

Every time a person fixes their own vehicle, an angel gets their wings. So, I'm glad you are digging in and working on it. But just remember, that when it comes to things like seals, gaskets, retainers, etc. That they are almost never unnecessary parts. So if you see something like a ripped gasket, it really needs attention before buttoning things back up. Something as important as the throttle body should be getting a relatively thorough visual inspection before being bolted back down. Otherwise you'll just end up learning the "true" function of that gasket later. Sometimes in a much more expensive, or frustrating way (like walking home in the dark, because the engine got toasted because it was running lean all the time). Definitely sucks when it is all due to a $4 gasket that would have taken about 5 extra minutes to install. Not trying to be negative at all, just hoping to encourage you to consider those details as your work on the Jeep, so that they don't bite you later and cause bigger issues.