TPI Help - Team Camaro Tech
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post #1 of 21 (permalink) Old May 5th, 11, 05:58 AM Thread Starter
Todd
 
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TPI Help

Ok, I will start at the beginning. I bought a 1992 Camaro Z28 with a 5.7 TPI. When I bought the car the person who I bought it from stated that it needed a new fuel pump and the car should be fine. He also said that he had the cat converters removed because they were bad.

At home I began with a visual inspection of the car. It has aftermarket headers, the person had removed the cat converters with a very poorly welded in straight pipe.

I check the fuel pressure it is perfectly fine, but the car turns over well, but does not start. I then check the spark plugs and wires. There were two types of plugs in the car and both were wrong, and the wires were two different types and both were old. I changed the plugs and wires with new ones. I used E3 plugs and factory wires. I had to remove the headers to get to all of the plugs, while the headers were off I discovered the positive battery cable going to the starter was nearly burned in two from the headers. I replaced the battery cable. After that was done, the car started right up with no issues. The fuel pressure is right at 40psi. I only let it run for a few moments because not all of the smog system was hooked up. I then reattached all of the smog system and put on the muffler which had been removed.

Again the cart started up with no problems, but shortly after starting the car began to stumble when I tried to rev the motor. In fact it was bad enough that the motor would spark knock and die. When the engine was running there was a sound of a very large vacuum leak. There is a tube that runs from the smog system to the cat converters I figured that this vacuum leak was the problem. I plugged that tube with a bolt. Still no change.

I then removed the snorkel for the air cleaner system and it was obvious that the air leak sound was coming from the air plenum. Specifically the IAC area. I removed the IAC and cleaned the carbon from it and reinstalled it, but no change. I removed the EGR valve and checked it. It is not sticking and it was not overly dirty. Still no change. The Map sensor that was on it had a crack in the top of it, I changed it and the problem has gotten worse.

At this point the car will start fine, and the vacuum sound at the IAC is minimal, but as the car warms up the vacuum sound get remarkably worse, and the car begins to stumble on its own. When cold the car will rev just fine, but only for a few minutes then it begins to choke its self out. When I press the accelerator it will die. When the car dies it will start right up.When the car is choking out the fuel pressure stays right at 40, or just below. I have not taken it to the shop to get put on a diagnostic machine, so I don't know of any trouble codes. There are NO check engine lights at all. Please help

Thanks

1968 Camaro, 1992 Camaro Z28 5.7
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post #2 of 21 (permalink) Old May 7th, 11, 09:44 AM Thread Starter
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Post Re: TPI Help

I spoke with someone at work yesterday and he said that he did not think that the fuel pressure was good enough. The Haynes manual that I have said that pressure is fine. It was his recommendation to change the fuel pump. I'm more inclined to think that the ECM is bad? I don't really know. I know that this is not the first time this has happened. Any pointers?

1968 Camaro, 1992 Camaro Z28 5.7
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post #3 of 21 (permalink) Old May 7th, 11, 12:28 PM
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Re: TPI Help

If the pressure is in spec when the engine dies thats not the problem.

Does it idle fine and just stumble when you hit the gas?

My money would be on a vacuum leak, failed sensor, or ignition issue.
Check for a vacuum leak by closely inspecting all the vacuum lines and spraying the sealing surfaces with something aresole and flamable, I use brake clean at work because its cheap and plentiful, carb clean or something else works. Just listen for the idle to change when you hit the spot.
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post #4 of 21 (permalink) Old May 7th, 11, 04:09 PM Thread Starter
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Re: TPI Help

It idles fine to begin with, but after a while it will stumble on its own, particularly after I have tried to rev it up. I have looked for a vac leak, but not to the extreme that you are talking. I will do that. When the car tries to stumble, I can spray some fuel into the plenum and it will run just fine. I thought vacuum leak, but IDK. I posted a couple of vids on youtube if your interested. Search 1992 Camaro 5.7 TPI problems. http://www.youtube.com/results?searc...+problems&aq=f There is more than one. Thanks for the help.

1968 Camaro, 1992 Camaro Z28 5.7
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post #5 of 21 (permalink) Old May 8th, 11, 08:46 AM
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Re: TPI Help

In looking at the present u-tube, I don't see any hoses from the charcoal cannister under the coolant bottle to the throttle body.

There is/should be a vacuum hose diagram, the yellow decal?, on the rad dupport or hood showing hose route. A good guide to follow.
Spraying into the t/body and engine speeding up is a good sign of an existing vacuum leak behind the t/body.

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post #6 of 21 (permalink) Old May 9th, 11, 04:46 PM
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Re: TPI Help

Like Everett said, check the vacuum lines.
One possible leak that is often missed is the brake booster, pull the vacuum line and plug it with you thumb, see if the idle improves.
Other than that just check all the hoses and sealing surfaces.
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post #7 of 21 (permalink) Old May 10th, 11, 01:06 AM
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Re: TPI Help

sounds like it changing when it from closed loop to open loop--vacuam line to fuel regulator ?
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post #8 of 21 (permalink) Old May 10th, 11, 08:37 AM
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Re: TPI Help

When cold started, it runs fine. When it warms up, it goes bad>>>>bad coolant temp sensor?

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post #9 of 21 (permalink) Old May 10th, 11, 03:49 PM Thread Starter
Todd
 
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Re: TPI Help

To begin with THANK YOU to everyone who has responded. Although at this point we aren't really any closer.

Yes there is a hard line hose that runs from the TB to the charcoal canister. It is located on the right hand side under another hose that goes to the PCV or a vent on the passenger valve cover. That is the only line that runs from the canister to the TB. There is no vacuum line routing diagram that I can see. The yellow sticker on mine is for the electric fans. (Which have not came on since I have owned this car.)

I have attached a picture that has the hose going to the passenger valve cover circled in red. When the car is running at idle this line has no vacuum or nearly no vacuum. It is undetectable if there is any at all. I would believe that a hose going to a PCV or vent would have a vacuum.

I have again checked the vacuum lines around the engine and I have found nothing out of the ordinary. The vacuum line going to the brake booster was good, and it has a very strong vacuum. Some of the vacuum lines around the car seem to be deteriorating, so I will change them, but none have been found to be bad.

The vacuum line going to the fuel regulator is fine. If i remove that line the fuel pressure goes up, but no other changes.

I don't know about the coolant temp sensor. The gauge works, so unless there is another sensor for the gauge?

I dont know about open loop or closed loop, it tends to run better when cold, but it does not run perfect (I attribute some of this to being cold). I have read where these cars go into a "limp home mode" I guarantee that my car does not have enough power to limp home.

I put a jumper wire in my diagnostic port to check the codes. I get nothing. My check engine light does not flash. It very quickly flashes when i first turn the key on, but no other flashes, it just stays lit.

I know that I have rambled on, but I'm at a loss you guys are my only hope before I take it to the shop.

1968 Camaro, 1992 Camaro Z28 5.7

Last edited by winstonwolfe; May 10th, 11 at 06:33 PM.
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post #10 of 21 (permalink) Old May 10th, 11, 05:19 PM
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Re: TPI Help

I believ ethe charcaol cannister hoses are on the drvr side of the throttler body, one large one 5/16 inch? and a smaller one, 1/8 inch?, going to the top of the cannister and used as a purge signal to open the valve on top of the cannister so ther charcoal can be 'dried' of fumes through the larger hose.

The circled hose is from the PCV on the valve cover and if removing the hose at the t/body does not give a vacuum, clean the port in the t/body and make sure the rest of the hose and valve are in good working order.

The ECM coolant sensor is under the thermostat housing on the vertical side and has a two-wire connector going to it. Remove the plug when cold and should measure resistance of over 5,000 ohms. Once the engine warmed up, remove the plug and measure it again and should be less than 200 ohms. Common problem, either the connector corroded or bad sensor. Coolant temp gauge sensor is on the drvr side cylinder head between the front two spark plugs, Cyl's 1 & 3.

Engine runs better when cold because its in 'choke' mode and ECM is delivering more fuel for engine to run. As engine warms up, less fuel is given.

No problem with the write up, the more the better and a better picture of the drvr side t/body.

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post #11 of 21 (permalink) Old May 10th, 11, 06:38 PM Thread Starter
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Re: TPI Help

Everett, Thanks for the reply. On the picture with the red circle my canister has a tube the hooks up directly underneath that tube that goes to the valve cover. No other tubes from the canister directly go to the TB. I will attach three pics of the TB. It is a larger vac line. There is another line that connects to the TB, it is a very small one underneath the TB on drivers side. I dont know if any of my pics get it, its very difficult to see when on the car.

It will take a couple days before I can have my buddy come over and give me a reading on that temp sensor. Does this sensor control the electric fans?

This forum does not like my pics...too big. I had to crop these. I hope that you can see what you need.

Thanks again
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post #12 of 21 (permalink) Old May 10th, 11, 07:13 PM
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Re: TPI Help

Thanks for the pictures, but I guess I made a mistake as to the other hoses connecting to the drvr side of t/body. The small one might go tot he cannister. Manual would tell.

The ECM coolant sensor tells the ECM how hot the coolant is and yes, ECM would turn on the fans, around 230F. An override would be to select MAX A/C and both fans should come on.

You mentioned you have a Haynes manual. Not the best, but better than nothing at all. I would open the book and try to relate the pictures to the real thing to see if some where, a vacuum line is off or something not hooked up. I'm sure you've done this until your're blue in the face, I can relate.

If you replaced the TPS sensor, it needs adjusting to set it at the correct value. You can back probe the wires, carefully shove the pointy end of the lead through the back of the connector, center wire and one of the others, and adjust for book value of 0.5 VDC? Check the book.

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post #13 of 21 (permalink) Old May 11th, 11, 05:06 AM Thread Starter
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Smile Re: TPI Help

Thanks again Everett! I will do more research with my manual and see if I can discover anything. I will also get both of those sensors checked. I have not replaced my TPS, so in theory it is fine. IDK what the person who owned it before me did. Which two wires do I test for the TPS? Does this temp sensor have this drastic of an effect on the way the car runs?

When I turned on the max ac the driver side fan came on. The passenger side did not. Maybe the car is not getting warm enough for the fan to come on? Its not running so long like you drove 30 miles or so.

Thanks again

1968 Camaro, 1992 Camaro Z28 5.7
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post #14 of 21 (permalink) Old May 11th, 11, 05:43 AM Thread Starter
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Re: TPI Help

When the car runs it smells unusually gassy, especially for a car running so lean. IDK if this info helps, IDK if all TPIs do this. It seem weird though.

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post #15 of 21 (permalink) Old May 11th, 11, 06:32 AM
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Re: TPI Help

The colored connector under your circle in your picture. Meter lead to the center wire of its connector and one of the other two wires remaining. One pair of wires selected will show close to 5 VDC, the other pair will show under 1 VDC, this is the pair to measure for TPS setting. Key on, engine off.

Car will run gassy because one, its cold, two, its correcting for a lean condition, vacuum leak maybe.

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