I normally work on my 5.7, and girlfriends 5.0.

But was doing a tuneup on a v6 1991 camaro.
Fuel injection.
I did not adjust the timing at all.

I changed:
Oil, oil filter, distributor cap, distributor rotor, wiresw, plugs, and air filter.

After the tuneup it ran good for about 1 mile. After that it wasn't that great.
and its to the point that I had to disconnect the battery for 20 minutes and reconnect and it helped it a lot. I even tried the EST disconnecting while running, turning it off and then reconnecting.

Thats the background.

Now, when its idling its fine, when I keep the gas pedal under 1/2 the way down it performs fine.
If i push the pedal further it seems to dog it as if the timing is slightly off or that its not getting a good enough spark/gas.

All of the vacums are connected / vacuumed.



Things I thought it could be.

ECU going bad with the EST?
Ignition module?
Fuel pump?
Fuel injectors clogged?


IF its ecu and EST can I:

disconnect the EST inline wire, and just manually time it and run it off of normal timing like my 5.7 and carb?

IF its an ignition module problem can I:
Replace it with the spare one I have for my 5.7? its same connectors and everything.

If its the Fuel pump is it in the same location on the block as a 5.7?

if its the fuel injectors can I just replace them?



Thanks for your time

 

the fuel pump will be in tank. to time it, you have to disconnect the est. and then set timing. Stock i believe is 10 degrees BTDC. I'll let some of the more knowlegeable guys step in and help you further. good luck

 

The timing didn't change at all since before the tuneup, marked it to make sure.

But when the EST is disconnected the timing is off.

So possibly the timing is off because of newer components?

Anyone know if autozone or advanced has a special wrench for loosening the retaining clip around the distributor? because soo much more stuff in the v6 than on my 350.

And Is there any problem with me running the car without EST? (computer wise)
my 350 only has 1 thing electronic on the engine and thats the spark for the wires.

 

could it possibly be a bad

http://www.partsamerica.com/ProductD...pe=412&ptset=A

? knock senesor?

 

When you dicsconnect the EST wire, you should have the timing set at 10*, if it's anything else, reset it.

It's unlikley that changing other parts messed with the timing.

If the Knock sensor is bad, you should still be able to set the base timing because the computer is no longer in coltrol of the timing and the knock sensor information is disregarded with the EST unplugged.

The hold down bolt for the distributor is a 15mm, you'll have to either use extensions and swivels or a shorty wrench to loosen it.

 

Forgive me please if I dont' quite get it the first time. I am not used to having a computer control the timing.

Right now when I rev the engine up it dogs it (with the computer controlling it)

Now, after resetting the computer(unplugging the negative for 20 minutes) it ran amazing for the first run.

Went to drive it today, horrible after going towards WOT.


I am pretty sure it will run better than it is If I adjust the timing without EST and keep the EST off. Right now with the EST unplugged it doesn't run well (duh?) at idle.

If I disconnect the EST, the knock sensor won't be used, and would it be all "normal" timing that I am used to? What would it effect? Gas mileage? a permanent error 42 code?
(im not sure what codes I have on it right now will be checking when I get home)

 

another good question: how was it running before the tuneup? IF the car begins to run badly, does it run better when it's cooled off or only if the computer is reset?

If you disconnect the est, the timing advance curve won't be used. It wont be "normal", althought there is, i think, timing added without the est over a certain rpm.

 

In about 35 minutes I will find out if it runs better "cool" and not computer reset. but when it ran really well it was after an hour cooldown and the engine was touchable, and the computer was reset.

Before tuneup:
I have been thinking about it.
It did dog it when you would want to go towards WOT, but I thought it was just because it hadn't had the sparkplugs changed in 2 years
That and I figured it was normal for the V6 for the weight of a camaro in comparison to me being accustomed to a 5.7

edit:

If I have an error code would it default to not use the "advance curve" ?

 

Only error code I get is 12

and it only seems to misbehave when its warm. idles at 1,000 rpms warm
higher when its cool.

only thing I can think that would be different than last was I have a vacum hooked up now that was loose before the tuneup.

Any suggestions?

 

i know the ICM is infamous for messing up when it;s warm.

 

ICM? being ignition control module, the one that has a plug going to the middle of the distributor?

the V6 version looks Identicle to the one from my V8 (which I have a spare one)
would It be feasable to use that?

 

Yes, the ignition module (not iCm) is the same as the one your v8 remote HEI uses. Just remember to put the thermal grease on it or you'll fry your spare up (Radio Shack sells a tube of "heat grease" if you can't find it at auto parts stores).

With the EST hooked up, your timing light won't tell you anything at all, so don't go by how the timing looks with EST connected. You need to unhook the EST to do anything with checking/adjusting the timing.

Did you double check the firing order? It's 1-2-3-4-5-6, with the #1 cylinder being the frontmost PASSENGER side cylinder. (This is opposite what V8 motors are.) If you're used to V8's, you might've used the wrong #1 cylinder.

While you're at it, check to make sure that at TDC of #1, the balancer mark does point at zero on the timing indicator. If the balancer has slipped (the isolation ring is rubber, and rubber deteriorates over time), then you'll need to replace it- but in the meantime you could make a "corrected" 0 degree mark on the balancer.

You "could" replace the injectors, but you should do a balance test first to find out which one(s) may be bad. If you don't have that equipment I'm sure a shop could do it for you...

My guess is, with the new parts, you uncovered a weak spot that wasn't there before. Fuel pump's a good place to check; you'll need a high pressure gauge for it (about $40 from pep boys/advance auto/etc). And you'd use that same pressure gauge with a balance test too.

 

you might try leaving the EST connector disconected and setting the base timming @ 28 degrees and drive it like that

 

Thank you for the replies.

It took me 3 hours of trying to figure out the correct firing order.....
yes i thought it was just like the V8... really annoyed me to find out that it was the opposite.

I RAREly do timing with a light, normally do it by feel going back and forth until it "fits" it correctly.

I have thought about that.

My plan of action was this.

Replace the ignition module (with the grease)

if still not "ideal"

Time it with the EST off by feel, then reconnect EST.

if still not "ideal"

time it with est off and drive without it.

if still not "ideal"

buy a brand spankin new ignition control module.

if still not "ideal"

breakdown and time it with a light, and repeat.


Thoughts now.
Only happens when its warmed up, I can lay down rubber with it from a cold start, I didn't notice this first because I normally try to let the engine warm up before driving.

Im really hoping its not the fuel injectors cause I want to get back to driving my porsche heh.

 

(laughs) I had done the same thing (messed up the #1 cylinder) way back when I first got my car (1994)! Good 'ol GM...

But- if the engine's started when cold, and left to idle until it warms up, that's when it drives poorly?

That does sound like the ignition module...

But if you've driven the car and went above 40 mph, the EGR might've kicked in. If the EGR valve is sticking, it could open (letting exhuast gas in) but it might not CLOSE! I think your car has the digital EGR so that's a lot of $$... but you could test it by making a blocking plate out of thin aluminum and putting it between the EGR pipe and throttle body.

Have you had a chance to check for spark once it starts acting funny?

 

I do not notice anything different at idle except lower idle speed.

I might get an spark tester, if the ignition module doesn't work too.

If there is a problem with the EGR, it will be definately be removed, along with a lot of the other pollution control.


EDIT:
Is the ICM that we are talking about this?

http://www.partsamerica.com/product_...X-LZ/LX340.jpg

or this?


http://www.partsamerica.com/product_...DR-DS/DR37.jpg

Cause I thought what we were talking about was the 2nd one.


Thanks again for the help

 

are you sure your not one connection off on your firing order? if so, the car would run, the timing would be off 20 degrees or something.

 

What I was getting at with warming up at idle versus warming up while driving, is that at idle, the EGR valve will never turn on.

On those pictures, neither of those is an ICM...

But the first picture is the ignition module, which is under your distributor cap. It's an 8 pin (6 external & 2 "internal") meant for all remote-coil HEI distributors. That's the guy you probably want to replace, or have tested, or swap in your spare... when they get hot, they stop working

Second picture is the ignition coil. That could've gone bad too, but usually they seem to last forever

EGR operation won't hurt your performance, its only activated at high-speed low-rpm driving (crusing on the freeway), not when you've got the pedal on the floorboard.

 

Ya, all I have is the ignition coil as a spare. I will try to pickup the module this weekend and replace it.

Where should I apply the heat grease?


In regards to the EGR to test it would Driving it 40 miles on highway (75 mph at 2,500 rpms) and coming to a stop and then turning off, waiting 5 minutes, and then starting it and still having the problem be the EGR?

Or Driving it below 2k rpms the entire trip?

Right now I am not pushing the pedal more than approx 3/8ths of the way.

Thanks again

- Firl

 

Ok, I replaced the ignition control module.
It still dogged it. BUT I also had to do this.
The battery was dead, had to jump start
I don't know if the battery is dead, will charge it tomorrow.
I am going to try another ignition coil, with a spare battery to see if that helps it.
After the ignition coil change, and new batter, I don't know what else to think.

And another odd thing, since the replacement of the alternator It has been pegged at 18 volts when the car is running.

Is it possible that a almost dead/very dead batter could cause that type of sputtering?

 

I kind of skimmed this... but it sounds like one of the spark plug's may not be torqued correctly, or one of the plug wires may not be on all of the way, or there may be a crack in a wire that is touching metal... Is it "missing"? I have a 2.8L v6, let me know if you need any help -- I have very little to minimal experience, but I also have my car in front of me for 2 days off

Oh yeah, what plugs did you buy, did you measure them right? When I change my plugs I changed the plugs, wires, diz cap and rotor (is it a rotor? whatever is under diz cap)

 

New wires, new plugs. I can re check them, but they are all in "harness spacers"

The car runs amazing on occasion. it is really odd to me. I just hope that its one of the things that I can do easily

I might try running it on normal timing to see if that helps.


- Firl

 

Firl,

You mentioned that you aren't 100% familiar with the 2.8L. You did mention you are familiar with the 5.0 and 5.7. In that case you may not be aware that when cold (or after you've given the motor time to cool off while you've got the battery disconnected) that the ECM ignores most sensors until the O2 sensor has had time to warm up and give a stable reading.

The fact that it runs well when cold leads me to think perhaps you have a malfunctioning sensor and the first one that comes to mind is the TPS (throttle position sensor). It works in conjunction with the MAF (if yours is a MAF car) or MAP to determine fuel/air ratio, and instructs the injectors accordingly.

TPS is a simple potentiometer and needs to be set properly. You might even have a dead spot halfway up your TPS. Since the ECM ignores most sensors when cold its possible that your ECM is ignoring the TPS's dead spot and letting the engine run well during that time period. Search is your friend and its worth looking into.

MAF (if its a MAF car) tells the ECM how much air is moving through the intake. If its bad you could have terrible high RPM performance as the sensor is much more critical at RPM than at idle. Test the MAF by just unplugging it. Note that you will force the car into using a standard fuel/air table based on TPS only. Economy suffers and it may cause emissions trouble, but if your problem goes away then you've solved it (bad MAF). I'm not certain if you can do the same with a MAP car.

EGR is another thing that comes to mind. At high RPM the ECM is telling the EGR solenoid to cycle on and off MUCH more frequently and keeping the EGR valve open a lot more. The ECM also takes the extra exhaust it instructed the EGR solenoid to add to the intake in terms of calculating injector duty cyle (air/fuel mixture), so a stuck open or closed EGR or a sticky EGR valve or a hard to open valve, or a faulty EGR solenoid could cause this to happen as well. (if the exhaust isn't present in the intake stream as expected the fuel/air ratio will be off).

If you haven't pulled the heads off I would even suspect a blown head gasket. A pinhole blow between 2 cylinders that doesn't really open until the head reaches temperature. I would check the plugs for adjacent fouling. Just like Scottie mentioned you might even have a dead cylinder from a bad wire or shorted plug, bad cap or out of round or tweaked distributor cap.

Timing should be 10 degrees WITH the EST disconnected. Advance is performed by the ECM via the EST.

Of course fuel pressure could cause ALL of this, check with a gauge and run the motor with a gauge to check for pressure drops or spikes. A bad injector would do pretty much the same thing.
And yes, you can just replace the injectors with OEM. 13# 15# and 17# versions that fit the hole will all work just fine. The ECM just compensates by adjusting width based on O2 readings.

 

The symptoms sound very similar to what my '88 was doing when I bought her. Turned out to be TPS wires resting on a valve cover and shorting out once she warmed up... may not be wires specifically, but I'd definitely consider the TPS and its circuit suspect until proven innocent.

 

I reseated the cap last night. I didn't check the wires too much.

"The fact that it runs well when cold leads me to think perhaps you have a malfunctioning sensor and the first one that comes to mind is the TPS (throttle position sensor). It works in conjunction with the MAF (if yours is a MAF car) or MAP to determine fuel/air ratio, and instructs the injectors accordingly."

Is there a way to tell the computer/ have the car operate all the time without sensors? to see it runs well all the time?

I will search on how to find out to tell if its a MAF or a MAP.



"If you haven't pulled the heads off I would even suspect a blown head gasket. A pinhole blow between 2 cylinders that doesn't really open until the head reaches temperature. I would check the plugs for adjacent fouling. Just like Scottie mentioned you might even have a dead cylinder from a bad wire or shorted plug, bad cap or out of round or tweaked distributor cap."

The car ran "ok" and didn't dog it this much before the plugs,wires,cap, rotor, icm.


"Of course fuel pressure could cause ALL of this, check with a gauge and run the motor with a gauge to check for pressure drops or spikes. A bad injector would do pretty much the same thing.
And yes, you can just replace the injectors with OEM. 13# 15# and 17# versions that fit the hole will all work just fine. The ECM just compensates by adjusting width based on O2 readings."

Pump is in the tank? not off the cam like on a v8?

Is it possible to just take the intake off/injectors, and put a V6 Carb manifold on and set the timing with the EST off and drive?

Im getting to the ammount of time in which that might take less, because I have a working spare holley 650 cfm, and know how to tune those.

I would much rather just turn off the sensors if possible to see if it is that.

- Firl

 

You said its a 91, its map.

Agree with the after it warms up, it runs like crap is a sensor not reading right. I would start with a TPS check (can do with volt meter).

Carefully clean the IAC.

Then I would replace the O2 sensor, its more then likely stock.

How is the vac reading? May have cracked a hose doing tuneup.

Usually when the ALT goes, it takes the ICM with it on these. Pull the alt off and have it checked.

Also make sure the cat isnt glowing red. A guy on another board had a cat problem and it would only act up above 3000rpm (on a 7k rated engine).


Also, does any of your friends have a ecm/data logger program for a v8 EFI engine? It could read all your sensors at once at tell you whats outta wack.

 

I now see why they call the toilet the think pot!!


ENGINE COOLENT TEMP SENSOR!!!!!!!!

In makes the car run like crap when warm.
in the front of the intake under the trottle body
black and yellow wires
19mm wrench
part cost 20 bux!

 

"I now see why they call the toilet the think pot!!"
I know what you mean.

"In makes the car run like crap when warm.
in the front of the intake under the trottle body
black and yellow wires"

Is it possible to just disconnect it and have it run without it?

The alternator is new, has less than 3k miles on it.

"How is the vac reading? May have cracked a hose doing tuneup."

I will look it all over tonight / tomorrow.

"I would start with a TPS check (can do with volt meter)."
Is there a reference site with correct resistances/volt readouts for all of the sensors? I can just go through them all


- Firl

 

If you dx the ECT, it will act in the "bad" way. So your better off leaving connected. Or dx'ing and see if it drives in the same manor.

The TPS should read a voltage of .50-.55 at closed. IIRC you check it between the black as the negative.. and... one of the others is signal with key on. the other will read 5volt with the key on, its not that one.

Surely there is a post somewhere with the correct info. Its a commen check item on EFI engines.

alt should not be reading 18v. Something is wrong(even if its the gauge). And yes, it may be causing the problem.

 

"Or dx'ing and see if it drives in the same manor."

Do you know how I would disconect it?

 

ok I changed:
MAP sensor
engine coolant sensor
engintion coil

Did not work

I heard one of the relays clicking ... alot and I could hear it inside of the car

I unplugged each one of them while the car was running one by one.


in Car.jpg its as if you were looking at the engine compartment with the radiator and batter at the bottom and the relays at the top A,B, and C

C relay turned the radiator fan off
B relay made the car almost die, and when gas was given, it did die
A was the relay that was clicking, and all the time
when A was removed it immediately sounded better
and ran perfectly fine... no problems.


I drove it around without the A relay which numbers read
0038 at the top and #141003304

I drew the relay diagram in Car2.JPG

I included the 35895.jpg as what the housing looks like.

now can anyone tell me what relay B and A do and why each caused each reaction?


history:

for past 2 years relay A had been clicking, but thought nothing of it.

- Firl

 

I believe that is the a/c relay....

 

bleh I figured it would be something unrelated to my problem.

Then could have unplugging b while it was running cause something to reset?

 

There are 2 sets of relays that *could* be in that location depending on the year and model.

MAF relay - MAF burnoff relay - Fuel pump relay.

I've seen them swapped in all different orders.

The other set is usually only 2 relays and is installed on a car with 2 cooling fans. It is for the 2nd fan I believe (or commonly called the A/C relay), the other is the fuel pump relay.

But I digress - Only 3 possible relays on a MAP car - fuel pump, A/C compressor, Cooling fan relay, This is according to the autozone wiring diagram from their website. I imagine relay c is the cooling fan relay. Relay B is the fuel pump relay, and relay a must be the A/C compressor relay.

Don't call it "unrelated" until you understand... A cycling relay that runs the mag clutch in front of the a/c compressor will wreak absolute HAVOC with the electrical system. You're talking about pulling 1/4 of the available power from the alternator on a very inductive load. Read simply, it will cause huge voltage sags in the electrical system, as well as intermittently placing a giant load on the belt from BOTH the compressor AND the alternator (from the increased load). EFI cars need STEADY regulated voltage. Having the a/c cycle on and off is a really good way to screw up the electrical.

Gratz on solving your very unorthodox problem

 

thanks, it just now has some problems idling, and will occasionally die when coming to a stop.

I still have to replace the o2 sensor, and go over all of the vacuum lines before i will have a better idea.


- Firl

 

Sorry this is a very late reply, but yes, that'd be an EGR symptom.

Doesn't matter how low/high your rpm's go, once the car's warm and you go over 40 mph, that EGR kicks on. And if it's rusted/gunked up, it may not release when the computer tells it to.

EGR will actually kick off if you floor the gas... it only engages while "crusing", not while accelerating/passing/racing. So if you were going over 40 mph the EGR could be on, then when you floor it to pass someone- the computer shuts off the EGR, then after you pass them- the computer turns the EGR back on.

 

how long is it to replace the egr valve on the 6?

on my v8 it only took 5 minutes to remove it.

looks like i will be replacing the o2 sensor and the egr valve at the same time hoping that it will work all out.


- Firl