Post Intake Woes
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
I reseated most connectors, but I suppose I should be thorough and do them all again. I haven't checked the fuel pressure but the fuel filter is almost new and I've already replaced the pump since the start of this issue, I've checked for leaking injectors and regulator. Do to the problem seeming to come and go predictably I'm doubting fuel pressure but I may check it anyway if I can get a gauge. I have had it bog down at wot when it's having the problem. I haven't tried starting it at wot but when I open the throttle some it does start easier.
I've still been scouring the board looking for clues. The previous owner did install a msd coil and some box under the drivers headlight, I'm not sure of it's purpose. I've read these can cause weird issues. Can someone tell me what this is and if my symptoms could be related?
I've still been scouring the board looking for clues. The previous owner did install a msd coil and some box under the drivers headlight, I'm not sure of it's purpose. I've read these can cause weird issues. Can someone tell me what this is and if my symptoms could be related?
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
Today's update: ok so I reseated all the connectors, I educated myself on the MSD 6AL that my car is apparently equipped with and after reading of how often they fail I bypassed it, I also replaced my ICM, and took measurements on my coil when cold and immediately following the issue. Cold readings were 8.9k Ohms on all terminals. After the problem started when the engine was at full operating temperature the readings were 10.14k Ohms. As I've never measured a coil after a change of temperature I'm not sure if they are supposed to change readings or not.
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
Ok may have found the problem if I'm testing this right. Reading the resistance of the secondary is found by placing the leads between the 4 pin electrical clip in connector on the coil and the post that connects the coil to the opti, correct? Thats where I'm reading the 10k ohms. Measuring the primary is done with one lead in the 4 pin connector on the coil and one lead on chassis ground or the neg terminal of the battery, correct? If so then I'm reading it as open or infinite ohms.
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
Still fighting this damn issue! Ok its not the 02 sensors, the ecm, or the coil. I also tested the fuel pressure and it seems to be normal. It holds when the car is shut down and acts like it should when it's running.
I'm kind of down to plugged cats, opti, or somehow a bad fuel injector or regulator.
Someone said the car should start ok with the plugged cats so I'm not sure on that one. I did feel the pipes when the car was starting up, before the cat was much much hotter than after the cat. When I start the car at WOT it starts right up when cold so that would lead me away from the opti I would think and onto the fuel injectors. The injectors however are less than a year old bosch IIIs not only could i not imagine them failing so soon but I've checked them for leaks by lifting the fuel rail and observing.
I'm so at a loss. I had the computer sent to the shop and they told me it had a bad chip and replaced it. I didn't notice a difference. After doing the 02 sensors last night it seems to run better when it's started up but still starts hard unless i open the throttle.
Can someone please give me anymore insight on where I should go next?
I'm kind of down to plugged cats, opti, or somehow a bad fuel injector or regulator.
Someone said the car should start ok with the plugged cats so I'm not sure on that one. I did feel the pipes when the car was starting up, before the cat was much much hotter than after the cat. When I start the car at WOT it starts right up when cold so that would lead me away from the opti I would think and onto the fuel injectors. The injectors however are less than a year old bosch IIIs not only could i not imagine them failing so soon but I've checked them for leaks by lifting the fuel rail and observing.
I'm so at a loss. I had the computer sent to the shop and they told me it had a bad chip and replaced it. I didn't notice a difference. After doing the 02 sensors last night it seems to run better when it's started up but still starts hard unless i open the throttle.
Can someone please give me anymore insight on where I should go next?
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
QUOTE:
Someone said the car should start ok with the plugged cats so I'm not sure on that one. I did feel the pipes when the car was starting up, before the cat was much much hotter than after the cat.
This is typically evidence of a plugged cat.
Someone said the car should start ok with the plugged cats so I'm not sure on that one. I did feel the pipes when the car was starting up, before the cat was much much hotter than after the cat.
This is typically evidence of a plugged cat.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
First of all, if I knew the fix for your problem I'd be more than happy to post it; however I don't. I could post guesses, but they'd be just that, GUESSES. So I figure we need to approach this in a different way.
It should be obvious by now that you need a Factory Service Manual and stop guessing at so many things. Posts 22 and 23 are examples. So there's no way you could rely on the voltage or resistance readings you get if you don't even know what they should be.
The manual's a great investment and this won't be the last time you'll need and refer to it. It has Trouble-Shooting trees for diagnosing your problem. If you take the car to a shop that's what they're going to do, trouble-shoot the problem to find the cause. So you'll be paying them for something you can do just as well and save that $$. For me, after all else has failed, a shop is the VERY LAST RESORT.
Guessing at the cause of the problem and, then, throwing parts at it isn't working. It's past time to move on to a more scientific/professional approach.
Jake
It should be obvious by now that you need a Factory Service Manual and stop guessing at so many things. Posts 22 and 23 are examples. So there's no way you could rely on the voltage or resistance readings you get if you don't even know what they should be.
The manual's a great investment and this won't be the last time you'll need and refer to it. It has Trouble-Shooting trees for diagnosing your problem. If you take the car to a shop that's what they're going to do, trouble-shoot the problem to find the cause. So you'll be paying them for something you can do just as well and save that $$. For me, after all else has failed, a shop is the VERY LAST RESORT.
Guessing at the cause of the problem and, then, throwing parts at it isn't working. It's past time to move on to a more scientific/professional approach.
Jake
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Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
Thank you but I have the factory service manuals, they've been no help. Nothing seems to directly relate to my problem. I tried looking up resistance and voltage specs but I've never seen a more poorly laid out book
Burning Brakes
Joined: Aug 2007
Posts: 917
Likes: 2
From: Charlotte NC
When I did the TB coolant bypass to my 94 I went ahead and cleaned the throttle body and installed new gaskets.
After I put it back together it did ALL the same symptoms you described down to the o2 codes. Somehow I damaged the MAF wile I had the TB off. Just by chance, I swapped out the MAF with one from a camaro I had at the time and it all went away.
A very quick, easy test is to unplug your MAF and start the car. It should idle high, But run fine if it is the MAF. If you unplug it wile running the engine will die, so do it first before you start it.
My MAF looked fine, The wire was still intact. It just went retarded for some unknown reason.
After I put it back together it did ALL the same symptoms you described down to the o2 codes. Somehow I damaged the MAF wile I had the TB off. Just by chance, I swapped out the MAF with one from a camaro I had at the time and it all went away.
A very quick, easy test is to unplug your MAF and start the car. It should idle high, But run fine if it is the MAF. If you unplug it wile running the engine will die, so do it first before you start it.
My MAF looked fine, The wire was still intact. It just went retarded for some unknown reason.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
There have been a LOT of occasions when I've had to go page by page in order to find what I was looking for. I've been tempted to throw both of them in the fireplace. Then I'm reminded how much they cost me so I come back to my senses, LOL
I'll bet the Trouble-Shooting tree you need is in there; it's just finding it.
Jake
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
When I did the TB coolant bypass to my 94 I went ahead and cleaned the throttle body and installed new gaskets.
After I put it back together it did ALL the same symptoms you described down to the o2 codes. Somehow I damaged the MAF wile I had the TB off. Just by chance, I swapped out the MAF with one from a camaro I had at the time and it all went away.
A very quick, easy test is to unplug your MAF and start the car. It should idle high, But run fine if it is the MAF. If you unplug it wile running the engine will die, so do it first before you start it.
My MAF looked fine, The wire was still intact. It just went retarded for some unknown reason.
After I put it back together it did ALL the same symptoms you described down to the o2 codes. Somehow I damaged the MAF wile I had the TB off. Just by chance, I swapped out the MAF with one from a camaro I had at the time and it all went away.
A very quick, easy test is to unplug your MAF and start the car. It should idle high, But run fine if it is the MAF. If you unplug it wile running the engine will die, so do it first before you start it.
My MAF looked fine, The wire was still intact. It just went retarded for some unknown reason.
Jake
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
Dang disconnecting the maf was no good. Thanks anyway.
Yeah with how much those cost I should gold plate them for display on the mantle piece. Someone from this site should rewrite them and use their own experience with common issues and fixes, organize it logically and sell electronic copies. If done right I'd pay decent bucks for it and ebay this garbage.
Yeah with how much those cost I should gold plate them for display on the mantle piece. Someone from this site should rewrite them and use their own experience with common issues and fixes, organize it logically and sell electronic copies. If done right I'd pay decent bucks for it and ebay this garbage.
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
If it was running fine before you replaced the intake manifold gasket, and now it doesn't it must be something you touched. It could be a pin in a connector has pushed in and not making real good contact. Cats do not go bad from just sitting.
Thinking while typing here....
Are you sure you got all the vacuum lines reconnected correctly? Is there someone near you with an LT1 that you could compare with?
Did you reconnect the temp sensor on the front of the water pump?
Check the coil wire and make sure it is seated on the OptiSpark.
This has got to be something simple...
Thinking while typing here....
Are you sure you got all the vacuum lines reconnected correctly? Is there someone near you with an LT1 that you could compare with?
Did you reconnect the temp sensor on the front of the water pump?
Check the coil wire and make sure it is seated on the OptiSpark.
This has got to be something simple...
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
If it was running fine before you replaced the intake manifold gasket, and now it doesn't it must be something you touched. It could be a pin in a connector has pushed in and not making real good contact. Cats do not go bad from just sitting.
Thinking while typing here....
Are you sure you got all the vacuum lines reconnected correctly? Is there someone near you with an LT1 that you could compare with?
Did you reconnect the temp sensor on the front of the water pump?
Check the coil wire and make sure it is seated on the OptiSpark.
This has got to be something simple...
Thinking while typing here....
Are you sure you got all the vacuum lines reconnected correctly? Is there someone near you with an LT1 that you could compare with?
Did you reconnect the temp sensor on the front of the water pump?
Check the coil wire and make sure it is seated on the OptiSpark.
This has got to be something simple...
Back Track and check/test everything you disconnected/re-positioned/replaced/etc. The cause is there somewhere.
Here's where "Attention to Detail" pays off. It's often the smallest thing. Something that looks "okay" but in reality it isn't.
Jake
Burning Brakes
Joined: Jun 2008
Posts: 892
Likes: 1
From: New Smyrna Beach Florida
Still fighting this damn issue! Ok its not the 02 sensors, the ecm, or the coil. I also tested the fuel pressure and it seems to be normal. It holds when the car is shut down and acts like it should when it's running.
I'm kind of down to plugged cats, opti, or somehow a bad fuel injector or regulator.
Someone said the car should start ok with the plugged cats so I'm not sure on that one. I did feel the pipes when the car was starting up, before the cat was much much hotter than after the cat. When I start the car at WOT it starts right up when cold so that would lead me away from the opti I would think and onto the fuel injectors. The injectors however are less than a year old bosch IIIs not only could i not imagine them failing so soon but I've checked them for leaks by lifting the fuel rail and observing.
I'm so at a loss. I had the computer sent to the shop and they told me it had a bad chip and replaced it. I didn't notice a difference. After doing the 02 sensors last night it seems to run better when it's started up but still starts hard unless i open the throttle.
Can someone please give me anymore insight on where I should go next?
I'm kind of down to plugged cats, opti, or somehow a bad fuel injector or regulator.
Someone said the car should start ok with the plugged cats so I'm not sure on that one. I did feel the pipes when the car was starting up, before the cat was much much hotter than after the cat. When I start the car at WOT it starts right up when cold so that would lead me away from the opti I would think and onto the fuel injectors. The injectors however are less than a year old bosch IIIs not only could i not imagine them failing so soon but I've checked them for leaks by lifting the fuel rail and observing.
I'm so at a loss. I had the computer sent to the shop and they told me it had a bad chip and replaced it. I didn't notice a difference. After doing the 02 sensors last night it seems to run better when it's started up but still starts hard unless i open the throttle.
Can someone please give me anymore insight on where I should go next?
Running normal in open loop (cold) then missing when going into closed loop is so typical of bad injectors.
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
I kept thinking it was something simple too. The vacuum layout isn't very complex and I didn't actually mess with that many systems to do this job. I actually replaced the coolant temp sensor again just to be sure I wasn't crazy. lol
Jimbo, you may be a genius a few days late. I actually ordered some new injectors from FIC on Monday on a hunch. Just finished putting them in and it seems to be running great! Smooth idle throughout the temp range and good power. It's still ever so slightly off but that may just be cause it's relearning since the computer was reset. I actually had new cats put on on wed because the old ones were original and I bet were bad anyway and with the new cats and these new injectors I can say I haven't spun the tires this easily from a roll maybe ever.
So I'm not releasing the final word yet because I didn't have much time to drive it today. In a few days I'll post what I found.
Jimbo, you may be a genius a few days late. I actually ordered some new injectors from FIC on Monday on a hunch. Just finished putting them in and it seems to be running great! Smooth idle throughout the temp range and good power. It's still ever so slightly off but that may just be cause it's relearning since the computer was reset. I actually had new cats put on on wed because the old ones were original and I bet were bad anyway and with the new cats and these new injectors I can say I haven't spun the tires this easily from a roll maybe ever.
So I'm not releasing the final word yet because I didn't have much time to drive it today. In a few days I'll post what I found.
Thread Starter
Intermediate
Joined: Oct 2010
Posts: 39
Likes: 0
From: Arlington TX
Oh Jake thanks for the suggestion. I've actually thought about them but I was not comfortable driving it there. It's nearly an hour drive from my location and I didn't want to damage anything. Have you had good experience with them?