I just took off my throttle body for the first time. It took me about a hour, most of which was trying to get the coolant elbow off. I couldn't so I ended up cutting it in half since I was doing the TB coolant bypass at the same time. I wanted to save the parts just in case, but oh well.

Anyways, I ended up breaking the locking tab off of the MAP sensor plug. I had to pull it to get to the coolant hose clamp. Will it hold in by itself or do I need to get a new one? I have my doubts since it's sitting vertically and plugs in on the bottom.

Other thing is even though I stuffed an old shirt under the coolant spout on the left side, coolant still ended up running down the back of the water pump (and probably the opti). Knowing my luck it'll come back to bite me in the *** later. If I had to guess I'd say 10-20 mL worth ran down over top of it and dripped down to the ground. Think I'll be the next opti thread?

Now, I have the TB sitting on my work table disassembled (will clean it tomorrow since I have no more time today). I noticed that the IAC motor is very badly caked with carbon and oil residue from the PCV/intake. My idle was fine however, before I did this. I don't want it to fail right after I put it back on though. I know you can't clean them, so should I just buy a new one or leave it?

Also discovered that it's the original factory coolant @55k miles and there's a lot of sediment in the TB coolant passage so I'm assuming the motor and the radiator contain equal amounts. So I guess the next thing on order for me is a flush and refill.

I keep finding all these neglected things in my car. I'll be busy this summer making up for 55k miles of crappy maintenance and abuse.

Thanks for reading this. I appreciate your thoughts.

Chris

 

You can clean the IAC but be very gentle; I used a soft bristle paint brush. After cleaning my TB I noticed the rpms would hang; I ended up applying a small amount of oil with a Q-tip to the TB butterfly rod where the rod enters the TB housing; cured the issue.

 

On the MAF plug, my tab has been broke for years and never had a problem with it coming unplugged. If yours is loose you might put a small dab of sealant on the outside part on the plastic so that it will "Glue" it in..but not too much so that it will never come off again in case you need to unplug it again.

 

The MAP sensor connectors seem to get brittle and break, causing intermittent contact. I'd get a new pigtail and replace it. Shoebox has the part #'s for the pigtails on his site:

http://shbox.com/1/4th_gen_tech1.html

The MAP reading is critical, affecting spark timing, long term fuel correction tables, etc. Fix it, don't take a chance.

Important thing on cleaning the IAC motor is to NOT try and turn the pintle, unless there is evidence that the pintle is not set to the correct length. Do not allow cleaner or oil to puddle in the sensor, risking it getting into the stepper motor. Again, I think Shoebox has info on his site.

 

I have yet to see an LT1 that has the clip on the map sensor, every one I have seen has been broken off.

 

I cleaned this thing really well, even cleaned out the coolant cavity even though it's never going to be used again, so it was pretty much pointless. I must say it turned out great, and I got out all of the carbon buildup.

I didn't even bother to touch the IAC motor as I was afraid of damaging it so I just put it back in without cleaning it. My idle smoothed out quite a bit, but it seems like I lost a good amount of low RPM torque. I don't know why. I sure hope I don't get stuck with one of those year long gremlin threads.

Firstly, did I change the airflow enough for the computer to have to relearn air/fuel table? The difference before and after cleaning was throttle blades were so caked with carbon buildup that the cleaner would just pool up along inside without running through and I couldn't see any light. After, ran through with blades closed and I could see a ring of light around the closed blades. I very much doubt it changed enough to cause this, but who knows...

The rubber elbow right below the PCV valve is cracking and dry rotting out. I think it's for the EVAP system? It was however, pretty bad before I took it off, though tampering with it may have opened up some of the cracks... not sure how bad of a vaccum leak I would have here if any. Either way I'm going to replace the elbow.

Like I said earlier I broke the MAP sensor clip so I guess I'm gonna replace that too.

I also have an exhaust leak right at the manifold gasket, I know it's probably causing me to run a little rich, but that shouldnt have changed anything since I cleaned the TB. Was kinda planning to wait till I could save up for some headers maybe the end of this summer... who knows.

I hate to discount the opti even though I'm pretty sure it's not it. My high RPM still feels ok and it wasn't missing at all to my knowledge. Also started right up after cleaning. This was after I did have some coolant from the throttle body run out passed my "catch shirt" and it ran down the back of the water pump and probably onto the opti. The other thing though is everyone with these low RPM problems change out the opti and it never helps anything.

One final thing, but I should mention is that I now have this weird noise like little tiny ball bearings rolling around on a marble floor. Also it kind of sounds like an electrical arcing really fast like. I'm 99% cure it's coming from the AIR check valve on the driver's side, as it kinda got quiter if I leaned in closer to the valve cover, but was loudest with my ear right up against the check valve. I don't think it's the plug wires or anything since they werent doing it before.

I feel like such a moron with this car as I can't seem to figure anything out...

Thanks for reading this long, any of your thoughts or ideas are appreciated.

Chris

PS I couldn't find the part numbers for the MAP pigtail or the EVAP elbow.

 

The part number for the 93 to 97 MAP wiring pigtail is 12085502. I just checked the price at a local GM dealer here in Toronto and they wanted about $40 which seemed to me to be a bit wild so I will see if I can get by with a bit of a bandaid solution like others on the board, or see if it is available elsewhere (NAPA/UAP?). I would think the part is fairly standard but you never know. Best of luck.

 

I had to replace the wires on my MAF sensor. The connector has long pigtails and even comes with heat shrink butt connectors.I got mine for 22.00 at the local dealer.Not that bad to do,I took my time and wrapped all the wires back into the factory loom.You can't tell it,except the connector is white on top.

 

No.

The PCV valve is in the middle of the drivers side of the intake manifold. Are you possibly talking about the EVAP connection on the side of the throttle body, which is below the hose connection that supplies fresh air to the passenger side valve cover, for the PCV system? If its the EVAP elbow, you have a vacuum leak that needs to be corrected.

When mine crumbled, the engine ran OK under normal cruising, but under full throttle at the track, the MAP signal was intermittently dropping to "0" under the vibration. You should be able to get the pigtail cheaper. As noted, Shoebox has the part # and sources for GM parts at discount prices noted on his website. Was your price $40 Canadian?

Why run it for any extended period with a problem that could be causing it to run excessivley rich, wasting fuel, losing HP and maybe even washing down the cylinder walls with excess fuel?

Use a metal rod or a stethescope to track down the sound. A leaking check valve in the AIR system can cause exhaust to get into the AIR pump, rusting it up and damaging it, and it also may be presenting yet another path for fresh air to enter the exhaust system and screw with the O2 sensors. If the check valve is leaking, you should feel heat building up in the rubber hose connected to the check valve.

Fix the obvious problems before you decide its the Opti and spend a lot of money.

 

Yes, I meant the PCV air tube, not the valve. Sorry for the confusion I was thinking faster than I was typing or something.


Ok, I was kindly provided the part number above so I am going to replace it.

Actually, I need some advice. I would really love to fix it, but how much do I need to take apart? I figured if I was going through all the trouble to remove the manifolds to replace a gasket that it would be better to stuff some headers there in at the same time. However, I am short on fundages and cannot yet afford any headers. So if there's a really cheap solution in the meantime then I would LOVE to fix this leak. It is driving me crazy. It's the very top of the #7 cylinder looks to be around the gasket, the bolts are snug and I didnt want to try to turn them any tighter to not to break one. What options would I have then or would I be biting the bullet?

As far as the noise is concerned I could buy a stethoscope and listen, but I've never used one before. Is it really obvious when you find where the sound is coming from or will it be sending me on wild goose chases?

Also I looked on shoebox's site and could not find part numbers for little things like that PCV elbow. Am I missing a whole section of his site somewhere?

Thank you for your time Injuneer and everyone else.

Chris

 

I don't think Shoebox goes down to the level of the vacuum hose fittings. Most of those are generic, and can be bought at local auto parts stores.

 

My MAP locking tab broke off 10 years ago and never had a problem, however it's always a good idea to replace it, for $8.50 buy a new one!

http://www.eficonnection.com/eficonn..._pigtails.aspx