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305 TPI, No Idle and backfires

Old 01-19-2016, 08:46 AM
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305 TPI, No Idle and backfires

Good morning everyone,


I have a 1986 IROC with a 305 TPI. The car has 40,000 miles on it. At 35,000 miles I replaces the plugs and wires, the distributer and rotor, and the fuel pump. The car has run flawlessly for the last few years except the fuel pump is starting to whine again...frustrating. Anyway, the car has been sitting for a few months. I have had the key on a number of times just to slip the car into neutral to move it around in the shop but I haven't started it. A few days ago I started it, it ran fine...for awhile. After about 10 minutes of driving the car it wouldn't idle and would die while driving it and the Check Engine light came on. Got the car home and it sat for 4 days. I started it yesterday and it started up fine and would idle fine for maybe 5 minutes then the RPM would drop to around 500 and almost die, the Check Engine light would come on, and it would then pick the idle back up. This went on for a few minutes, almost dying then coming back. After a few minutes the car would just die.


I have read a few posts and its a little overwhelming. I am going to start by changing the fuel filter, that is easy. I'm curious if anyone has had the exact same symptoms as my car and could advise my next step or check? I already have a new MAF sensor, Fuel pressure regulator, and an idle air control valve in my cart to buy. I figured I would send out a quick post before I started throwing parts ($280) at the car.


Thanks in advance to anyone who has read this far into my post, it is much appreciated!!


Greg
Old 01-19-2016, 09:01 AM
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Re: 305 TPI, No Idle and backfires

Good morning. I would check the TPS/IAC and see if it's in check. Also, your injectors are pretty old, Check into buying some new ones from SouthBay Fuel Injectors on here, cant go wrong. Change the fuel filter, can't hurt.

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

And before you make a major purchace of a new MAF...read this. And if needed, get a NEW one.

Good luck!
-Bob

https://www.thirdgen.org/forums/tpi/...6-replace.html
Old 01-19-2016, 09:46 AM
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Re: 305 TPI, No Idle and backfires

Originally Posted by Bob88GTA
Good morning. I would check the TPS/IAC and see if it's in check. Also, your injectors are pretty old, Check into buying some new ones from SouthBay Fuel Injectors on here, cant go wrong. Change the fuel filter, can't hurt.

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

And before you make a major purchace of a new MAF...read this. And if needed, get a NEW one.

Good luck!
-Bob

https://www.thirdgen.org/forums/tpi/...6-replace.html


Bob, I sure appreciate the response. I will see if I can make the adjustments this weekend.


Greg
Old 01-19-2016, 09:56 AM
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Re: 305 TPI, No Idle and backfires

Any idea on the check engine code it's throwing? If you could some how data log what's going on, that would surely help you. It looks like it could be when the ECM enters close loop after 300 seconds (5 minutes of open loop when engine is cold). In open loop, it usually runs pretty rich.

Maybe an O2 sensor failure?

Best of luck!
Old 01-19-2016, 10:02 AM
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Re: 305 TPI, No Idle and backfires

Originally Posted by SbFormula
Any idea on the check engine code it's throwing? If you could some how data log what's going on, that would surely help you. It looks like it could be when the ECM enters close loop after 300 seconds (5 minutes of open loop when engine is cold). In open loop, it usually runs pretty rich.

Maybe an O2 sensor failure?

Best of luck!
Agree SbFormula! Forgot that one!
Old 01-19-2016, 10:04 AM
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Re: 305 TPI, No Idle and backfires

Originally Posted by SbFormula
Any idea on the check engine code it's throwing? If you could some how data log what's going on, that would surely help you. It looks like it could be when the ECM enters close loop after 300 seconds (5 minutes of open loop when engine is cold). In open loop, it usually runs pretty rich.

Maybe an O2 sensor failure?

Best of luck!

I am going to try borrowing a reader to pull the code(s) this weekend. I agree, that will help you guys diagnose my issues much easier and more accurately. I have an O2 sensor in my O'Reilly cart after reading some more posts this morning.


Thanks for the response,
Greg
Old 01-19-2016, 05:07 PM
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Re: 305 TPI, No Idle and backfires

are you SURE its a new MAF ?? if there is even the slightest chance its a re man from "spectra" or worse "cardone" . smash it with a hammer. new ones are costing $381 by themselves. and you say you want to spend $280 total . something aint addin up
Old 01-20-2016, 09:29 AM
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Re: 305 TPI, No Idle and backfires

O2 sensor?
Old 01-22-2016, 02:34 PM
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Re: 305 TPI, No Idle and backfires

Originally Posted by rusty vango
are you SURE its a new MAF ?? if there is even the slightest chance its a re man from "spectra" or worse "cardone" . smash it with a hammer. new ones are costing $381 by themselves. and you say you want to spend $280 total . something aint addin up

Sorry for the late response, been away from my computer.


It is a reman MAF from O'Rielly's
Cardone Remanufactured - Mass Air Flow Sensor
Line: A1 | Part # 74-4712


it is a Cardone ($159), which is sounding like its a waste of money...assuming I need it. Autozone has a duralast reman for $129. I'm going to try hooking the car up to a scanner this weekend for more clues.


Greg
Old 01-22-2016, 03:02 PM
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Re: 305 TPI, No Idle and backfires

AutoZone has a brand new unit for $127.99 part# DL-6014. The reman one they carry is a relabeled cardone that is almost as expensive as oreilly. The new on e has a lifetime warranty which is a plus too.
Old 01-22-2016, 06:49 PM
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Re: 305 TPI, No Idle and backfires

Originally Posted by jkris53406
AutoZone has a brand new unit for $127.99 part# DL-6014. The reman one they carry is a relabeled cardone that is almost as expensive as oreilly. The new on e has a lifetime warranty which is a plus too.
man , dont waste your time or money going to "vato zone" . i have confirmed , oreilleys can get a "rich -porter" brand new MAF for $381. i went through MANY re man MAFs before i got wise. PN MA157
Old 01-22-2016, 07:03 PM
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Re: 305 TPI, No Idle and backfires

Just had this same issue about two months ago. Started car up fine. after about 10 mins of idleing, gave it a little gas and it back fired and stalled out. could not get the car to restart. it would just crank until the battery started to die. I checked for fuel pressure at the rail, checked plugs and wires, checked to see if I had any codes, there were none. after all that I pulled the cap of the dizzy only to find that the rotor was burned on the edge. put a new rotor cap in and its been running great ever since. I hope your fix is as simple as that. I know I wasn't expecting that to fix the issue but it did.
Old 01-23-2016, 06:17 PM
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Re: 305 TPI, No Idle and backfires

Check this price.
https://www.google.com/url?sa=t&rct=...L5UWAEEIeNc2jw
Old 01-23-2016, 06:38 PM
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Re: 305 TPI, No Idle and backfires

Or how bout this AC DELCO one?
http://r.search.yahoo.com/_ylt=AwrTH...bWLy1Td91Fem8-

Last edited by mjdavis68; 01-23-2016 at 06:43 PM.
Old 01-25-2016, 08:16 AM
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Re: 305 TPI, No Idle and backfires - UPDATE

Good morning everyone!! And thanks to everyone who has replied!!


JD Z28, I'll check the rotor hopefully later this week. I did replace the cap and rotor, plugs and wires about 4,000 miles ago so I doubt that is the issue but your symptoms sound identical to mine so its worth a shot.


I had a very frustrating weekend with the car. I had a friend from a local GM shop bring his scanner to my shop. The car would do the circuit check but it wouldn't get anything else from the computer, no codes...nothing. He said this was a sign of a bad ECM. This was news to me. He said to test it, we had to pull the ECM out and do a 'Slap' test. Anyone heard of that? Supposedly this is a test you do, with the car running. You pull the ECM out and slap it. If the car dies then the ECM is bad. We slapped the ECM a few times. The very first 'slap' resulted in the car idle stumbling but not dying. We slapped it a few more times and the car died. Has anyone heard of this? I have read all the responses and also a number of other posts but I have yet to read anything about these symptoms being related to my symptoms.


More to come later. Thanks again for everyone's responses, its very much appreciated!!


Greg
Old 01-25-2016, 05:00 PM
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Re: 305 TPI, No Idle and backfires

I also pulled the ignition control module and had it checked. mine was good but just another possibility.
Old 01-25-2016, 05:03 PM
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Re: 305 TPI, No Idle and backfires

Have you confirmed that you have both fuel and spark??
Old 01-25-2016, 05:35 PM
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Re: 305 TPI, No Idle and backfires

Hi sorry I'm having similar issue and trying to post a thread and I can't figure out how.any advice? thanks
Old 01-25-2016, 05:40 PM
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Re: 305 TPI, No Idle and backfires

pull the o2 sensor wire and see if it runs any better.


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