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Old 01-13-2005, 08:36 AM
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1983 2.5 chevy eng problems

Ive been scratching my head on this one. So hopefully someone hear can help. A little history, I bought a 1983 camaro with a 2.5 tbi unit plus its a standard trans . It was kind of a basket case. I like the challenge. Well first after a manual and a box full of parts removed from the engine. I got it to run. further diagnosis, cyl head cracked, replaced it. Ok, moving on, runs so so. so I run it in the field mode, check the codes, egr bad, replace. Also time it in the field mode after replacing major tune up parts . still dont run very well so I repair exh leaks change o2 censer, boil out carb, check compression, all around 105. recheck field codes shows no errors and still runs bad. check for vacuum leaks seems ok. What it is doing , it will idle for a little but serging and die. It starts right back up and does the same. cant rev it at all just dies. checked fuel sys and filter, seems ok. only thing Ive seen comparing the book to the eng is # 1 is in a diff place but firing order is correct. Hopfully someone has some insight that I might be missing. Thanks in advance.

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Old 01-13-2005, 08:58 AM
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I know you said you checked the fuel system. Did you replace the fuel filer? How are the injectors? What kind of a signal are you getting to the injectors?

Just some thoughts, with the idle going south and not able to rev.

Pappy
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Old 01-13-2005, 09:18 AM
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thanks for the reply papy. I have replaced the fuel filter. I even ran the pump with the key on in a bucket, it filled very fast. With everything hooked together it cycles like it should, while maintaining pressure. It has one nozzle in the center of the carb. By watching it run, there is a nice mist. As it dies the mist stays the same until eng not rotating.
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Old 01-15-2005, 08:15 AM
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Now I will be going out on a limb..... Injection is not my strong suit.

Have you checked the Mass Air Flow? It sounds like it might not be reading right with the mist staying the same, even when it is about to die. Inlet temperature sensor, coils, maybe something else.

Hopefully one of the other guys who is a lot better with injection can educate me here too. Carbs are one thing, these are something else.

Pappy
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Old 01-15-2005, 09:24 AM
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my thought

I have an 88 2.3
I don't know if its the same configuation.
On the drivers side of the head is a vacuum pod. (EGR valve)
Disconnect it and put a golf tee in the vacuum line.
These cars are notorious for the EGR valve to get over sensitive.
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Old 01-15-2005, 09:43 AM
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thanks again pappy, Yesterday I tried to do a little elimination testing, I diconnected the tps and it wouldnt run at all, then diconnected the IAC and it wouldnt run then finally the MAP sensor it ran smooth for a couple of minutes then died. But wouldnt start backup. I cleared the codes and put a different MAP sensor on . Back to the way it was again. I can put it in the field mode it idles great but I cant let it run to long the exh pipe starts to glow red . The tag on the car says to time it on 8 deg between #1 and #4 . That is where its at. So hopfully this update will help someone to see something I have missed. Thanks
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Old 01-15-2005, 11:15 AM
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egine

When i ran my engine shop i had some of these do this after a rebuild. Try taking the exhaust loose at the manifold . then start car and see if it still runs the same. Some had the cat. pluged so tight it could'nt run.
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Old 01-15-2005, 07:35 PM
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Man o Man.... What have I been thinking. I would have to agree with swvalcon!

My '95 Impala was running like crap and it was the cat. Pipe got red and everything. Don't know why I didn't remember that. Good thing there are so many knowledgeable on the board.

Drop the exhaust like swvalcon said and if it runs better, when you drop the cat I'd bet it will weigh about 100lbs. Has the cat been changed? Let us know what happens. I would be interested to know.

Pappy
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Old 01-16-2005, 08:12 AM
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Excellent point. I didnt even think of the cat. I went and tried loosening the exh. But no difference. So I looked under the car, someone has removed the cat. Looks as they put a different muffler on also. I havnt had the car that long so havnt been under it. I was hopeing that was the problem. I drained the fuel and put all new in. Still the same. It also has a block heater so I plugged it in for a while and let it get warm. Ran smooth and quiet and no shaking for a little longer than it has before. After it dies again its hard to start. Re checked the codes, no codes. Im not sure what else to try.
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Old 01-16-2005, 08:36 AM
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I went back and reread your first post and I know you said you changed the major tune-up parts. There was a statement that grabbed my thought:

"only thing Ive seen comparing the book to the eng is # 1 is in a diff place but firing order is correct."

When you timed the car, did the distributor ever come all the way out/pulled for a look over?

Could the distributor be a few teeth off? I don't remember if these motors had the nylon gearing on the cam or not. Could it have jumped time?

The reason I ask is because in your last post you said:

"Ran smooth and quiet and no shaking for a little longer than it has before. After it dies again its hard to start."

I've had other motors run at idle but, still be out of time when you power them up. What kind of timing light are you using?

I know that some of this may sound silly , but you've got me stumped too. Hopefully this or some others suggestion will get it right.

Pappy
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Old 01-16-2005, 09:23 AM
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Pappy, I sure appreciate you going the extra mile with me on this. I find myself going back to the dist. also, because its not the way the book shows. I think Im going to pull it and clean it. Then set it accordingly. Ive looked in differnt manuals, it shows the #1 to be facing to the rear of the eng and shows the dist cap mounting screw pointing to #1. But doesnt show where the main wire connector points. So im quessing you can rotate the housing any direction as long as the plug wires are correct. I have a fox valley timing light, it checks RPM and advance. Will post back after I have done it. Thanks again.
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Old 01-16-2005, 10:14 AM
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Sorry but i must say this ! Repairing 2.5 4 banger in a Camaro !! What a waste of $ and Time!!
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Old 01-16-2005, 12:09 PM
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Just a thought.
Check the idle air motor. I have an 82 2.5 fuelie, on a buggy I built. Similar problem. Idled poorly/no acceleration/ dies. Never had the hot exhaust, though.
If you look down the top of the TBI unit, you should be able to see the tip of the idle motor needle, down the idle air intake port. It should be moving, as the engine tries to stall out. I replace mine with a used one from a mid-80's S-10 2.8. worked fine, but needed to be adjusted a little bit.
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Old 01-16-2005, 07:36 PM
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Oh, cmon roy, Its a classic. Factory t-top, the body is in excellent shape and it was cheap. Plus its different. Thanks for the input packratwrecker, as soon as the dist is back in. I will check into that also. And pappy I pulled the dist. and it has metal gears. I cleaned it up. Going to install it in the morn.
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Old 01-17-2005, 06:13 AM
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You know i have a 1992 Buick Century with the 2.5 with 280,000 miles and i just put the third timing chain set in !!, the tensioner always gives up and the chain breaks. IT has a bit of blow by now. but runs fine! I do have a few SBCs around if you need one ? This Is a Hot Rod Site!
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