Slow2.8

89 2.8 Camaro

Vacumn should b round 16, right? *gauge on the back of upper plenum small hose * I just took off the upper/lower plenum and the bolt on the fuel rail that holds the wire harness/rail to the lower plenum is stripped but the bolt on the back is good. Wondering if this could be part of the problem, the injectors looked sealed all around. Going to use propane tommorow and see if I can find the leak. Another question is could a bad maf/incorrect timing cause this low of vacum? Also throwing a code 34 and this is why I ask. New ignition module/cap/rotor also. My air filter is pulling in the same amount of air as when the car ran good, by the sound of it at least...

*new gaskets and rtv sealent. All bolts GNT with a little force after. *

Appreciate any help/tips.

Slow2.8

well im about to go get a used maf at the junkyard to see if it helps unless someone tells me its not worth it....

sloick

get a maf

Slow2.8

ya thats what I am going to do. tapped on the maf and the engine started to run better. I didn't know a bad maf would throw the vacumn off like that so I was stumped for a while looking for a leak....

Maverick H1L

iTrader: (8)

Engine vacuum doesn't just depend on how well the engine and associated vacuum-powered accessories are sealed and connected. Having an incorrect fuel mixure (generally lean with a bad MAF) will throw it off as well, as well as under or over-advanced timing, catalytic converter condition, etc.

BTW, before you go ahead and pay for the j/y MAF, take a look inside and make sure the frequency film is perfectly flat. If not (you can tell by using the film to look at a light) if it looks anything other than smooth, it's bad, and you'll continue to have problems.

Slow2.8

the film inside was a little bumpy. when running I tapped on the maf to listen for a change and it started running better. I recall someone saying that is a bad maf so I went ahead and ordered a lifetime warranty one from advance (microtech 80$) and will let you know tommorow. Thanks for all the time and help. I have till friday to get my state inspection or they tow the camaro .... SO I once again send great thanks to all on thirdgen.org

Slow2.8

Well the new MAF didn't solve my problem. Back to square 1. Timing is at 10 degrees right when I start her up w/ est disconnected. My guess is the lower plenum needs to be retorqued.

Maverick H1L

iTrader: (8)

Get yourself a can of starting fluid or something, and start spraying vacuum hoses with it. If the engine runs better, there's your leak. You can also take it to a dealer or a shop and have them use the vapor control system (smoke) test on your vacuum system to find leaks.
Also, check your MAF relay by swapping it with the fuel pump relay.
Other than that, you need to check your injector o-rings, the connection for the vacuum block in the TB, the seal at the brake booster for the check valve, the EGR and canister solenoids, and even the "orb of power" under the driver's side battery tray.

2_point8_boy

Wih vacuum that low you have a problem with a leak somewhere. Fuel mixture and timing will not bring your vacuum down 8-12 in. RTV is very bad to use on the machined surfaces of the plenum since it just squeezes right out. I have never used RTV on any fiber gasket on ANY car and have never had a problem.

The code 34 is because of the low vacuum problem. Use some Brake/Carb clean or propane to find your leak. Chances are that you have a pinched seal somewhere. With a leak that big, you should be able to hear it.

Just curiosoty here, but why did you remove the stuff to begin with. Are you chasing another problem???

Slow2.8

Well i feel dumb as hell since it was the ground to the maf relay the whole time *not connected * . That took care of the code 34 and brought the vacumn up to 15. With the timing at 10 deg. (est disconnected) the car still isn't running right though. It pops consistenly under acceleration. Put in 6 gallons of high test and still pops. Advanced timing to 12 degs, runs better but still pops. The fuel injector o - rings looked good and I re oiled all of them. I removed the plenum to paint the bottom red and polish the top. Main reason was to redo all the vacumn hoses with original stock pieces (had to rig up the pcv with air hose since it was broken) So the top and bottom of the plenum didn't even need rtv... good to know, hopefully it doesn't hurt. When I gave it some gas the vacumn gauge moves up and down very fast. Then resets to the 15 range. TPS set at .55.

Slow2.8

Going to try to advance the timing somemore and will check bak with the results....


... advanced it from 12 to 14 and the idle sounds like shhhh. put it back at 10* vacumn is still at 15 but fluctuates bad, up and down, when reving the motor. My gauge says this means weak valve springs. Could this have something to do with it? No codes are displayed now since I have the maf working again... Dont hear any vacumn leaks nor did I find any with propane. I do have a decent size exhaust leak on the passenger header connector, can feel hot air blazing out and when I seafoam the motor smoke rises from underneath. But I've had this same problem (exhaust leak) when it was running good. Sunday I'm going to check over some other Ignition Components, plugs, wires, and the coil. Sorry for such a long post just frustrated. I also put a fuel can of seafoam in the tank and I might do a whole can through the intake tonight. Fingers Crossed for that to work!