91REDZ28VERT

So my car had been sitting for a while ( 2 years ) and it would not start, after a lot of searching, reading and asking ( thanks to this site ) I figured it was injectors. so I drained the fuel, put fresh gas and replaced the fuel filter. changed the oil and filter, new air filters and pcv. installed the new injectors last week, it fired right up but ran rough.


I let it sit that night the next morning I started it and ran fine, until it warmed up and then started hesitating with slight miss and kind of rough idle. A friend of mine said he had the same issue and it was defective gaskets (runner/plenum). So I replaced the runner, plenum and throttle body gaskets and it made no difference.


So after reading some more (on this site) I read about the starting fluid test so I got the engine up to temp and sprayed an entire can of fluid around all the base/runners/plenum and no change in idle or anything.


My car has 32k original miles, can the plugs and wires cause this? Bad IAC? Bad Map sensor? Bad cap and rotor? Bad TPS?

It's strange to me that it runs fine cold (first ten minutes of driving) it gets rough the next 30-60 min. then really bad after an hour or so. Any help is greatly appreciated.

91REDZ28VERT

So this morning I started it and drove it around, I did not get that 10 min of good running that got the last two days now it just misses and rough idle....... Any Ideas?

bigal55

iTrader: (1)

Any codes? If it happens when it warms up, I would check the CTS. Could be something getting hot and breaking down, like the ICM. Just a couple of thoughts.

Tuned Performance

iTrader: (92)

check basics, wire ohms, corrosion on the coil wire !

91REDZ28VERT

Forgive my ignorance, but what is a CTS?


I had the ICM tested until it got "warm" and it tested fine. I just bought the plugs, wires, cap and rotor. I will install them tonight and see what happens. I did check for corrosion on wires/terminals when I had the initial issue of not starting and there was none.


Could a bad coil cause this?


Can a vacuum line leak cause this?


Thanks for the replies, I really appreciate it.

Tuned Performance

iTrader: (92)

Cts, is the coolant temp sensor. This is located on the rh front of the intake manifold and has a yellow and black wire going to it.

Tuned Performance

iTrader: (92)

[QUOTE=91REDZ28VERT;5912926]Forgive my ignorance, but what is a CTS?


I had the ICM tested until it got "warm" and it tested fine. I just bought the plugs, wires, cap and rotor. I will install them tonight and see what happens. I did check for corrosion on wires/terminals when I had the initial issue of not starting and there was none.


Could a bad coil cause this?
I wouldn't think it's the coil breaking down , sounds like the engine isn't going into closed loop, or the cts reading is off. The ECM may think the engine is colder than it is added unnessary fuel.

Can a vacuum line leak cause this?
A vacuum leak if it's minor would cause a high idle.

Thanks for the replies, I really appreciate it.

91REDZ28VERT

Ok so I got the new plugs, wires cap and rotor (was seized on there). I also obtained a obd-1 code reader and it threw code 12 (blink-blink, blink), 22 (blink, blink-blink, blink), 33 (blink, blink, blink-blink, blink, blink) and 44 (blink, blink, blink, blink-blink, blink, blink, blink ).

TPS read .75 to 4.80, if I disconnect it completely it runs really bad (same as if it warms up real good). I can't adjust it, only rotates about 1-2 degrees I pulled it of and it has no room for adjustment in the mounting holes.

Code 22 says "TPS - Signal Voltage low".

Code 33 says "MAP sensor- Signal voltage is high at idle (Note: Engine misfire or unstable idle may cause this)". So I assume that this because of the problem and not the actual problem.

Code 44 Says "Lean exhaust indicated ( left side on dual oxygen models)".

can a bad TPS sensor cause this?

I ordered the CTS it was not too expensive.

Like I said as of this morning it no longer runs "good" for the first few minute of running, like it did yesterday. It only goes from bad to worse. It does not smoke, knock or tick.

91REDZ28VERT

Ok so I disconnected the battery, installed a IAC and CTS. Connected the battery and wen for a drive to get it up to temp....... Through all this it still ran like crap,


SES came on again. Code 22, 33 and 44 not present but now code 43.


Code 43: EST (Electronic Spark Timing low voltage/ESC (Electronic Spark control) circuit problems.


Any Ideas?


Or is it time for an LS1?

Tuned Performance

iTrader: (92)

Start with looking under the passengers side for a melted blue wire going to the engine block or a brittle and broken knock sensor connecter.

91REDZ28VERT

Thanks, I bought a new knock sensor so while I am under there I will replace it. I will work on it tonight. New ECM is $99 I am thinking of just replacing it anyway.

91REDZ28VERT

Ok I installed the knock sensor but its still idles kind of rough and lacks power, I don't know where to go next. The only thing left is the ECM and the TPS. The wiring is good no corrosion or bad ends, I am at a loss.


Can it be the timing?


A bad ECM?


A TPS going bad?


Weakening fuel pump?

Tuned Performance

iTrader: (92)

It's hard to say what's going on, taping on the ECM to see if it makes a running change. Checking the fuel pressure and timing would be a good idea.
Having a older OTC scanner is a valuable tool to moniter sensors. The blue wire on the tps is the feedback wire idle or key on you will see .67-.76vdc.
The map can be tested with the key on as well. The reading based on atmospheric pressure and your altitude.

Tuned Performance

iTrader: (92)

http://www.robietherobot.com/Storm/mapsensor.htm
Yours is a 3 bar sensor .

91REDZ28VERT

After about 30 min of driving around it still runs rough, not at its worse but not good. after replacing the Knock sensor there are no more trouble codes. There is a vacuum line like 1/8" going from the Throttle body (driver side bottom) going into a "valve", and from the "valve" to the EGR. there is no vacuum coming from the line at idle and barley any at around 2k rpm. Also that "valve" which both lines connect into has terminal with a few wires going into it. What is that and should I replace it anyway.....


I do not have a timing gun so I have to wait until Monday to get the timing checked. What should timing be set at?


the fuel pump I have not checked yet either (we got snow and hail today).


Can a failing O2 sensor cause this?


Like I said there is no more check engine light.


Also I did get the Alternator chack and it passed.

Tuned Performance

iTrader: (92)

The egr is vavle solenoid is hooked up to the bottom of the throttlebody and does y over
To the ccp charcoal purge canister. This is a ported vacuum signal.
If rough idle was noticable after 160-170f it could be the o2 sensor.
Once the engine is warmed up you can unplug the o2 sensor. You may need to increase the engine off idle to heat the o2 so it will become active. With a volt ohm meter on a milivolt MV dc setting the o2 output will be going up and down from 9mv down . This is easier to see on a needle analog vom. If the o2 is stuck at .450mv range it's dead.
With the engine warmed up and the est wire disconnected. That wire is a tan with a black stripe located bye the havac blower housing. Set the timing to 6 before top dead center.

91REDZ28VERT

Thanks, I will work on it all day tomorrow...... I have been searching the forums for as much info as possible, so I have lots of testing to do.

Tuned Performance

iTrader: (92)

I hate to tell people throw parts at something or buy tons of tools.
You might look into renting a compression tester. Just so you could rule out mechanical condition. The passenger side plugs 6&8 and easier to remove from under the car.

91REDZ28VERT

That is one of the tests I was going to do today, but it ran fine lots of power thins morning no rough idle (drove it for about an hour)' I shut it off but now its crappy again.

91REDZ28VERT

Ok fuel pump with switch on shows 40 psi, engine started and idling its at 40 psi, press on the throttle and it jumps up to about 45 psi, back to idle 40 psi, engine of still at 40 psi.

No compression testers at the parts stores today. I am going through every terminal and connector to clean them while looking for any sign of a bad wire.

I also got my inspection camera so I can look in areas that are hard to see. I will post anything I find. Thanks for the replies. I am driving it around to warm it up so I can test the O2 sensors.

no new tires

sub-

TylerSteez

iTrader: (3)

Code 44 Can be caused by a clogged up egr. When my car had that dreaded code it ran like a dog, replacing the egr fixed the issue for me but my idle still isn't perfect.

NCC-2569

iTrader: (1)

You replaced your injectors. How is your cat doing?
If unburnt fuel made its way into it and then ignited inside it, it may be dead, depending on how much fuel it got.
Anything rattling when you hit the cat?

91REDZ28VERT

Hey guys, I've been busy, so I ran the car tonight and got under the car cats not glowing. When it was cold I shook it (as much as I could) and no rattle. Now I got a code 12.....


Code 12: No distributor signal to Electronic Control Module. ICM tested good several time, coil pick up tested good. Should I just replace the distributor?

Like I said there is no corrosion on any of the terminals or wires. The distributor does have some corrosion, I had to "pry" the rotor off. I have not had the timing checked, it barley stopped raining today.

Thanks for the replies and suggestions, I really appreciate it.

Tuned Performance

iTrader: (92)

KOEO checking codes there is no distributor reference signal. Code 12 will show entering into diagnostic mode.

TylerSteez

iTrader: (3)

Code 12 means that diagnostic mode is working, it should show up every time you check codes

91REDZ28VERT

Ok so when it blinks "code 12" in groups of 3 repeatedly, it means diagnostics mode is working? I just want to confirm.


So my wife took the car this morning and when she got back she asked about the puddle of "oil" on the passenger floor board. I knew immediately that it was coolant, so I pulled the lower panel to investigate the leak and as soon as I removed the lower panel the ECM slid down from under the dash. wiring was still connected but it was not mounted.


Now I know I need to replace the heater core, another 5 hours of work this weekend.


The ECM is a Reman and was just dangling around under the dashboard it does not look like it got wet but the coolant puddled near it on top of the lower panel. So there was definitely moisture close to it. I am going to have the ECM tested some time this week.




Are these ECMs prone to failure? I ask because it $45 to test them and that's half way to just buying a new one. Also I assume there is a way to "mount" the ECM or is it just suppose to dangle?


Thanks for the replies

TylerSteez

iTrader: (3)

Yep all is fine with code 12.

That sucks the heater core went, definitely not a fun time to replace. As for the ecm, I wouldn't say they're prone to failure. Very rarely they're the cause of any problems but it does happen from time to time. I personally wouldn't be too concerned with it as long as it isn't acting different after you've noticed the coolant. I can't remember how they're mounted, it's been a while since I pulled the kick panel down. I'll try to find some info on that and post back to this thread

TylerSteez

iTrader: (3)

A quick search on thirdgen lead me to this thread.

https://www.thirdgen.org/forums/body/242993-ecm-mount.html

Seems like you need a plastic bracket that secures the ecm. I'd start by locating the screw holes for the bracket so you know exactly where it needs to go and then search around junkyards for a thirdgen with one. If yours is a 91 then I found one online for ya, pretty cheap too.

http://shop.thirdgenbargainbarn.com/products/ecm-bracket-90-92-camaro-firebird

http://www.thirdgenranch.com/90-92-camarofirebird-ecm-mounting-bracket

91REDZ28VERT

Ok thanks, that bracket is there. The ECM was not in there, thats why I asked, this ecm seems to be too big to fit in there.


Will it interfere with anything if I bypass the heater core? My main goal is to get the car running like it use to. After which I am going to replace the core, pump, thermostat, radiator and install a lower temp fan switch. All I would have to do is connect the two hoses that go to the core right? I have limited time to work on my and would rather spend 5 hours getting it running than under the dash.

TylerSteez

iTrader: (3)

Bypassing won't interfere with anything, just no heat lol. and yep, just connect those two hoses and you'll be good to go

91REDZ28VERT

Thanks, right now in New Mexico its too hot to have the top down, so I can do without a heater.

91REDZ28VERT

Ok so I ordered a ECM and Monday I will also get a new distributor and coil..... Hopefully I will have it all installed by next weekend, I will install one item at a time and drive it between installs, so I will know which one the problem was :-) assuming this fixes it. If not I wil know what the problem wasn't.

onefreakz

keep us updated , im having the same driving conditions

91REDZ28VERT

I will post all results until the car runs like it did, its needed a torque arm bushing since I've had it, and when I'd stomp the pedal it would thump! Now its not even noticeable.

91REDZ28VERT

Ok so far the biggest PITA was pulling off the heater hoses from the heater core. once off I connected them and replaced any coolant lost. In case anyone needed to know the heater hoses are not the same size one is 5/8" and the other is 3/4".


So I first installed the distributor, the only tool needed was a 9/16" crows foot. I marked off the old one, oiled the new one and installed it. took all of 15 min. So I fired it up and NO change. Kind of disappointing since I was thinking it was the coil pickup or the ICM.


Anyway, I next installed a new coil which seemed to make a minor difference. To remove the bracket I used a coarse file to file the broad side of the rivets, like 5 passes over each rivet and they fell out.


I am waiting for the ECM to get here, I will let you all know how it turns out, at this point I am "shooting in the dark". I am still waiting on compression tester/gauge. I may take it to have the compression test done, unfortunately where I am, a good mechanic is hard to find.


Thanks
TJ


Next on the list are the O2 sensors, MAP sensor, TPS and any other sensor I can buy. I may disconnect the cat just to see if it makes a difference? Can I damage anything by doing so?

PurelyPMD

iTrader: (3)

Try fogging it with Seafoam & adding some to your gas tank. Read the directions & do it properly & you may clear up your rough running issue - it did with mine.

Tuned Performance

iTrader: (92)

You can't damage anything with the cat out of the picture. Prolonged running with the exhaust short may burn a valve but testing your fine.if you do get a tps the adjustable 85-89 tpi one is cheaper for some reason. Back proble the blue wire and black wire or ground. Key on set to .67-.76vdc .

91REDZ28VERT

Thanks,

The local part store had the TPS for the 88 Z28 and it was half the price of the 91 TPS.

I have it on hold and will get I this evening.


Again thank you all for the replies

91REDZ28VERT

Ok so my ECM came in I installed it and there was no difference, also while waiting for the ECM I got it timed.

I also got the tps sensor, as I was installing it I broke the tps connector on the harness. So I need to find a new one. My voltmeter crapped out on me so I will deal with it tomorrow.

As of now the only sensors that I have left to replace are MAP and O2's. I was unplugging injectors and the only one that did not make a difference when unplugged was cyl #2. So I will have to investigate that.


At this point I would rather put another motor and be done with it. I am seriously considering an L98 swap, Monday I will do a compression test, and I will know for sure.

Tuned Performance

iTrader: (92)

http://m.ebay.com/itm/370663217699?nav=SEARCH
Sounds like you have narrowed it down to number 2. Real bummer if it has low compression in that hole.

91REDZ28VERT

Thanks for the link I just ordered the connectors.

A friend of mine told me that the factory cylinder can be "tapered" and if the engine sits for a long period, the piston rings can get stuck in their ring grooves from carbon, if the piston was sitting in the narrow end of the "taper", causing the cylinder to "leak".

He also said that there is a possibility of the #2 injector being clogged from residual dirt in the fuel line. I was told to use a mechanics stethoscope to listen to it.

Through all this, when I moved to the house I'm in now, I had my tools in "storage" and half of them walked away. Its interesting the cheap tools are still there but the "expensive" ones grew legs.

Tuned Performance

iTrader: (92)

Bad luck on the tool
I didn't add this link, a great tool for replacing those old brittle connecters .
http://m.ebay.com/itm/361262579444

91REDZ28VERT

Hello all, I have been really busy and have been driving the car in the mean time, its gotten better. I had the compression tested and its good. The shop I took it to said the #2 injector may be clogged, and suggested I replace it. I will let you all know how it goes. I am ordering the injector tomorrow.


Its running better after all the work I did, still not 100%, but I would say about 90%.....Thanks for all your help thus far,I will keep you all posted.

bottledbird68

In for updates. Chasing issues myself and looking to see if you come up with anything I haven't lol

PurelyPMD

iTrader: (3)

My new 91 was running rough after warming up. Not so much the first time I drove it but got successively worse each time. Replaced injectors with Bosch III's (noisy), replaced the coil, removed the MSD, and replaced the ignition module. Put 30 miles on it last night & it's an animal!

A little over $200 in parts & some time cleared all ills.

91REDZ28VERT

Hey guys,

So I ordered another set of injectors, bought a crap load of tools and I am waiting for good weather...... I live in central New Mexico and we get rain like every other year, but the last month has been raining every weekend.

I do promise to update any work i do to the car until runs like new or put a new engine in it :-)

onefreakz

91red any updates

91REDZ28VERT

New set of injectors installed today, torqued everything down, new torque arm bushing and just finished detailing it............... Runs and drives like new. So its done, my car is 100% back to working order, now I need to install a heater core and see why the A/C is not working. Also needs a mild sound system.


Thanks for all your help guys!

onefreakz

Awsome good news . Thanks for all the info