When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi all,
I have searched the interweb for an answer to my problem, with no success.
My car is an 86 coupe, steel heads.
It has:
-new fuel pump
-new injectors
-new FPR
-new knock sensor
-relatively new plug wires
-relatively new cap, rotor and coil
air pump removed.
Cats removed
I only drive the car occasionally. It had been running good, with a slight miss at low RPM.
Started the car up for the first time in two weeks, now it's running like crap - it starts up fine, then it misses, runs rich, backfire after revving and closing throttle.
The TPS reads 0.4V throttle closed, 6.0V throttle opened. Cannot get it adjusted to within specs (0.5V-5.0V). So Im getting a new TPS, but certainly this can't be causing the problem.
Timing... I *think* that the base line timing is correct... I say "think" because the only timing mark on the crank pulley is a diagonal line.. no straight perpendicular mark to be seen...
So what do you think? Could it be time for a new dizzy?
Something else I should check?
The timing mark will NOT be on the pulley....it will be on the balancer itself....and it will be a straight grove going from front to back also.
An EGR can ave a small thin piece of carbon that can get stuck and not allow the pintle to seat properly...and you can have a really bad idle....sometimes so bad that it can cause the engine to die.
Hopefully the poster got the TPS in and adjusted correctly.
DID you replace the fuel filter also?????
You are aware that routing your plug wires correctly is IMPORTANT...ESPECIALLY where they go under your distributor ( cylinder #'s 1,2,and 3)....they need to stay away from your four wire connector that goes to the distributor.
DO you have a scanner?????
Did you verify fuel pressure????
You still have an O2 sensor...correct????
Is it stored outside under a car cover????
Is it stored outside with no cover and it gets rained on????
Reason being....you could have moisture issues...A.) in the distributor cap if is ash been raining a lot and water is getting trapped due to the car cover not breathing as well as if it were not covered at all. B.) Water getting in the fuel tank due to the drain boot being clogged...AND YES...IT HAPPENS.
The timing mark will NOT be on the pulley....it will be on the balancer itself....and it will be a straight grove going from front to back also.
An EGR can ave a small thin piece of carbon that can get stuck and not allow the pintle to seat properly...and you can have a really bad idle....sometimes so bad that it can cause the engine to die.
Hopefully the poster got the TPS in and adjusted correctly.
DID you replace the fuel filter also?????
You are aware that routing your plug wires correctly is IMPORTANT...ESPECIALLY where they go under your distributor ( cylinder #'s 1,2,and 3)....they need to stay away from your four wire connector that goes to the distributor.
DO you have a scanner?????
Did you verify fuel pressure????
You still have an O2 sensor...correct????
Is it stored outside under a car cover????
Is it stored outside with no cover and it gets rained on????
Reason being....you could have moisture issues...A.) in the distributor cap if is ash been raining a lot and water is getting trapped due to the car cover not breathing as well as if it were not covered at all. B.) Water getting in the fuel tank due to the drain boot being clogged...AND YES...IT HAPPENS.
DUB
Timing mark. Yes I meant to say on the balancer. There is no perpendicular (front to back) groove. I sanded all the rust off and nothing. Just a diagonal line. Bizarre.
The EGR has been removed. The AIR pump and valves, etc. have been removed.
I'll check the IAC as per playsdixie suggestion.. although the car is rich throughout the RPM entire range. So not sure if that's it.
I'll check the o2 sensor as per jgalfo's suggestion - although it's not that old.
I do not have a scanner. I've looked at them but can't decide which one to get.
As for diagnostic tools, I only have the TPS diagnostic harness tool.
I've just ordered the diagnostic harness tools for o2 sensor, MAF, IAC.
I went over the vacuum lines... no leaks.
Fuel pressure... I had a cheapo fuel pressure test guage from Harbor Freight, and the part that screws onto the schrader valve started leaking all over the place. Threw it away. Will get a name brand fuel pressure tester this weekend to check fuel pressure.
The car does have a new Edelbrock fuel pump and fuel filter with less than a 1000 miles on it.
Plug wires: DUB, I was not aware of keeping them away from the four-wire connector... I'll check the correct routing.
The car is acting like it has a vacuum leak and timing is way off.
The bizarre part is that it started acting this way suddenly...and this is where DUB mentioned something that might be an issue...
the car is always parked indoors... but, I rolled it out the other day to wash it... after I washed it I went to start it and that's when it started acting like crap.
Gonna get to the bottom of this. I'll get back to y'all with an update. In the meantime, if you have any more suggestions, fire away.
If you measured 6 volts on the TPS then there is a problem somewhere, either in the ECM or your meter. The ECM supplies a 5 volt reference to the TPS. You need to measure this with respect to the ground wire on the TPS, not some random metal part of the engine. The middle wire on the TPS should measure 0.54 volts at idle. The ignition has to be on but the engine does not have to be running to check this.
Are you checking the timing with the EST wire disconnected? It is a tan wire with a black stripe and the EST connector is next to the windshield wiper motor. If you can't see the timing mark then it's possible that the outer ring of the harmonic balancer has shifted.
If you measured 6 volts on the TPS then there is a problem somewhere, either in the ECM or your meter. The ECM supplies a 5 volt reference to the TPS. You need to measure this with respect to the ground wire on the TPS, not some random metal part of the engine. The middle wire on the TPS should measure 0.54 volts at idle. The ignition has to be on but the engine does not have to be running to check this.
Are you checking the timing with the EST wire disconnected? It is a tan wire with a black stripe and the EST connector is next to the windshield wiper motor. If you can't see the timing mark then it's possible that the outer ring of the harmonic balancer has shifted.
I'm using an inline diagnostic plug (the kind with the alligator clips) from Ecklers to check the TPS voltage. Ignition on, engine off. If showed 6 volts WOT. But, I will check it again with another voltmeter.
If it still shows 6V, then do I assume that the ECM is bad? Or are there ways to check the ECM? I guess if it turns out to be a bad ECM, then that would explain why the car is running like crap?
Timing. I did unplug the EST to check the timing. No line on balancer. Just that diagonal line that (coincidentally) crosses at 6 degrees.
Harmonic balancer. Not sure what previous owner night have done... But there are no timing marks. I checked the whole way around. Maybe I should get a new balancer in order to be able to time the car properly.
The ODDS that there is NO notch in the balancer is about a million to one. IT has to be there. It JUST HAS TO. BUT...even if it is there is NO GUARANTEE that the outer ring is in the correct location so if you do go and time the engine..it will be correct...UNLESS you go through a process to verify Number 1 TDC....which I do often. Getting a balancer with the correct notch may be the way to go.
I would not worry about a new ECM ...yet. I would see if you can get the TPS adjusted correctly as Cliff mentioned ( .54 volts ).
Verifying the fuel pressure is important also.
When you wash ed it...you DID NOT wash the engine compartment area ...DID YOU????
Are you sure that the drain boot around your fuel neck is flowing water???? If not....it is possible that water got into the gas tank.
The ODDS that there is NO notch in the balancer is about a million to one. IT has to be there. It JUST HAS TO. BUT...even if it is there is NO GUARANTEE that the outer ring is in the correct location so if you do go and time the engine..it will be correct...UNLESS you go through a process to verify Number 1 TDC....which I do often. Getting a balancer with the correct notch may be the way to go.
I would not worry about a new ECM ...yet. I would see if you can get the TPS adjusted correctly as Cliff mentioned ( .54 volts ).
Verifying the fuel pressure is important also.
When you wash ed it...you DID NOT wash the engine compartment area ...DID YOU????
Are you sure that the drain boot around your fuel neck is flowing water???? If not....it is possible that water got into the gas tank.
DUB
I think I figured out why I could find no timing notch
Seems to be the wrong balancer or installed backwards.
Bizarre. At least I found the timing notch now.
I guess I'll shop for a balancer.
Wash job: no, engine not washed. Hood was down but not latched shut.
Drain by fuel filler cap. Yup it was partially blocked
I blew some compressed air down the drain tube and muddy crap
spewed out the bottom.
Replaced battery in my voltmeter. Now tps reads 0.54v at idle, 4v at WOT.
Gonna use a buddy's voltmeter to check it again
NO...your balancer is SHOT and NEEDING TO BE REPLACED!!!!!!!! I am surprised if the balancer outer ring.....which has slid back....has not rubber a hole in your timing chain cover. I have serviced MANY balancers that look just like this one. MAKE NO MISTAKE ABOUT IT....GET A NEW BALANCER. So shopping for one is IMPERATIVE!!!!!
Glad that you posted these photos. No I see what you were seeing. AND...that you actually employ advice and suggestions that people give you. I am glad that you blew out your drain tube at your fuel boot. Keep an eye on it from time to time.
If your car were in my shop....and knowing that water is heavier than gasoline...I would siphon out your fuel and check it and see if I see a separation where water was actually in the fuel tank due to this OBVIOUSLY plugged drain hose for your fuel boot. NO LIE....I drained out 5 gallons of gas in a 1989 years ago and got it running again. SO do not ASSUME that you are OK.....Like I mentioned...i would check the fuel due to MANY issues can be attributed to fuel contamination or quality. if you have a factory service manual...it is written in many areas for issues of the engine not running correctly.
You obviously do not have 5 gallon of water in the fuel tank...but I know I would HAVE TO check your fuel if I found the drain boot hose plugged and you have just washed it and it began to run really bad. The again...I have a set-up for SAFELY removing fuel easily...because I have to do it several times in a year.
NO...your balancer is SHOT and NEEDING TO BE REPLACED!!!!!!!! I am surprised if the balancer outer ring.....which has slid back....has not rubber a hole in your timing chain cover. I have serviced MANY balancers that look just like this one. MAKE NO MISTAKE ABOUT IT....GET A NEW BALANCER. So shopping for one is IMPERATIVE!!!!!
Glad that you posted these photos. No I see what you were seeing. AND...that you actually employ advice and suggestions that people give you. I am glad that you blew out your drain tube at your fuel boot. Keep an eye on it from time to time.
If your car were in my shop....and knowing that water is heavier than gasoline...I would siphon out your fuel and check it and see if I see a separation where water was actually in the fuel tank due to this OBVIOUSLY plugged drain hose for your fuel boot. NO LIE....I drained out 5 gallons of gas in a 1989 years ago and got it running again. SO do not ASSUME that you are OK.....Like I mentioned...i would check the fuel due to MANY issues can be attributed to fuel contamination or quality. if you have a factory service manual...it is written in many areas for issues of the engine not running correctly.
You obviously do not have 5 gallon of water in the fuel tank...but I know I would HAVE TO check your fuel if I found the drain boot hose plugged and you have just washed it and it began to run really bad. The again...I have a set-up for SAFELY removing fuel easily...because I have to do it several times in a year.
DUB
Thanks DUB.
I'll get a new balancer and check the timing chain cover for damage.
Draining tank. I do not have a factory manual. I do have a Haynes manual. Haynes says to drain the tank by uncoupling the fuel line at the filter and letting gravity take over. You mention siphoning the gas out. I don't mind either method... But....
Is siphoning better?
The gauge says I have a quarter tank, so... 5 gallons, give or take.
I have a metal tube that can go down into the fuel tank with a protected end on it. It will take the fuel from the bottom of the tank...thus any water.
This is why I do not use a Haynes manual. The reason is....the "Haynes' method will only allow for so much fuel to come out...which depends on how close the pick-up sock is to the bottom of the tank in the reservoir. Which is why I do it like I do it...and in most cases...I pull the sending unit IF I have a lot of water in the fuel.
Also..as stated in the GM service manual...the filter sock on the bottom of the fuel pump is designed to not allow water to pass through it...UNLESS it is IN WATER. BUT...that is assuming that you do not have a tear in the sock..which I have seen before...thus will ALLOW water to get sucked into your fuel system.
IF you do or do not find water in the fuel....replace the fuel filter due to it is a moisture trap by design also. Especially if you do not know when it was last changed. Make sure you go by GM and get the 2 special 'o' rings for the fuel filter fittings also...so just in case they are badly smashed and weird looking...you can install new ones.
Well, I think I just opened up Pandora's box.
Took the harmonic balancer off.
Then I decided, since I was this far, to inspect the timing chain. Of course by taking the timing chain cover off, the one-piece oil pan gasket gets damaged. Oil pan gasket removal is next. But first... The timing chain has a ton of slop in it... Very loose.
Any recommendations for new timing chain?
Anyway, once it get the oil pan gasket replaced, timing chain set and cover reinstalled, and new water pump (this one might be the original one... I don't know)...
Then, I can get back to the business of draining the tank, checking the timing, and hopefully resolving why it's running so rich. Fwiw, all 8 spark plugs were black, indicating to me that all 8 cylinders are rich (as opposed to one leaky injector).
Bringing this thread back to life... after many months of life happening, I am able to work on the Vette again. New balancer, and while I was there, new timing chain, new timing cover, new water pump.
So, I try to start the car, thinking it might actually work. Turns over, doesn't catch. Used to run pig rich... now doesn't catch.
So, taking advice I had received last year in this thread, I went to investigate whether there was water in the fuel..
Took the fuel pump/sending unit out:
WTF? Note the rust and black gritty crap all over the place
Peeked in the gas tank. Uh-oh. Not good. Siphoned out 2 gallons from the tank into this bucket...
So...
2 things... (1) I need to figure out how this happened, to prevent it from happening again,
and (2) clean the tank, lines. I'm hoping the fuel filter caught any crap from entering the fuel rails or injectors...
Cleaning the tank... the right way to do this would be to remove the tank and clean it that way... but removing the tank out of a C4 looks like a real b!tch... so I'm going to see how clean I can get the tank with it still being in the car.
Progress report. Cleaned out the tank and fuel lines.
The tank had sludge, rusty grit, and other floaties in it. Using carb cleaner, I think I got the tank back to an acceptable state.
Except:
The [what appears to be a] seam between the top and bottom halves... It looks like it has rust.
Wow, Ive never seen that much gunk in a gas tank before and I have revived several vehicles after years of sitting. One had been thru several floods and wasnt that bad.
The tank look fine, dont worry about that little bit of rust. Blow out your fuel lines, install a new pump, sock, and filter. Go get some Chevron gas if available or buy some Techron/Techroline from AZ or WallyWorld. It will take care of what little gunk may be left and clean up your injectors. That will cover the fueling side.
Make sure all the basic electrical measurements are good. Minimum idle, TPS, IAC count, and timing. Fuel good +electrical good=running car. If it runs badly again, take it to a parts house and get them to scan it for you. You can also "rent" them to check them out to help you decide what you like. I cheaped out and got a clearance price on a really good OBD1 scanner whos name escapes me but it was made by Hughes Electronics. It has the capability to take a "snapshot" of diagnostics which helps if you experience a problem at a certain rpm range.
10-12-2014, 03:52 PM
86 missing, running rich.
