Did fuel injector cleaner cause problem? - ZR-1 Net Registry Forums

Z Factor · 03-01-2007

Well it could be more than one issue but you would not be the first person to dump fuel injector cleaner into a ZR-1 and experience problems as a result. However the good news is that your concern about the flywheel is probably unfounded as a poor running LT5 can cause it to sound bad.

As to a Chevy dealer being able to properly diagnosis the problem, I'd say it is possible but unlikely. My guess is that you will need to replace the injectors, but before you do anything you need to have a knowledgeable person look at it. Aaron would be an excellent choice, but of course he is a decent distance away. I'd call him and see what his thoughts are.
There is a guy down in Miami that is very good, but I do not know if he has the time since he is so busy. . I can check with him for you and see what his schedule is like, so just let me know.

tomtom72 · 03-01-2007

L'dawg, When you checked the MAP sensor you checked the electrical plug or you checked the plug and the hose?

The issue could be just coincidence although injector snake oil stuff is not advised...only the Techron stuff from Chevron I was told by a GM tech that that is what GM sells over the parts counter in a rebox.

Ya gotta pull the SES DTC(trouble code) & post up, or look it up if ya have a FSM(by Helm). If ya have or know some one with a scan tool with the correct software pkg for your yr Z you could run a scan and compare your data to the data in the Helm FSM. Section 6E, "Emissions and Driveability" chapter is where the codes are listed and the section has a page with what the scan data of a normal LT5 looks like in closed loop.

Usually he early 90 thru 92(?) injectors are the most problematic...they were designed before the ethanol was added to the fuel. So if you're in that group then the injectors are a prime suspect. The later cars seem to be less susceptable to the ethanol. Only thing with failing/failed injectors: the effects don't go away off idle....they can cause a miss but it's permanent till r & r is done. There are two modes of inj failure: coil shorts and nozzle junk. Shorts cause a non firing = lean cylinder. Junk can be either lean or rich because the junk disturbes the spray pattern....neither condition will necessarily set a "code" (DTC) because the injectors are monitored indirectly by the ECM...via the O2 sensors mostly.

The thing is if your miss is real & only at or just off idle speed then I would ask if it gets worse as the car gets to proper coolant temp? It's kind of okay when stone cold? It's there when cold but gets worse as she warms up? All those point to injector coil shorting....in that scenario the injector's short will get worse the more heat gets to the coil and that's the give-away to shorted coils, the miss doesn't go away rather it gets worse. If it is injectors it will get much worse as time passes...the miss that is.

I would also do some looking at all your vacuum connections and pull the plugs for inspection, oh and do a spark test while you're there. The more you can eliminate in the absence of a scan tool the further all of us might have some ideas to pass along. The scan makes it easy but diagnostics can be done without one....it's just back to basics. Ya know does it smell rich or lean, the fuel filter is new, the PCV's are good, the vac connections are all in place & there is no sucking noises, Your vac gauge says it's not lean or rich. You get the idea, right? Oh, yea the spark test will help you eliminate the wires and coils...ya know pull one at a time when shes at idle?

Sorry to be so long winded about this!

Good luck & post up!
Tom

tccrab · 03-01-2007

If your Z is a 90-92 most probable cause is fuel injectors.
Been there, done that.
If your Z is a 93-95, could be plugs, wires, coils.

Start and warm up your car until in closed loop. Pull the plug wires carefully one at a time and listen to the sound of engine. The engine should stumble and miss and sound different when you pull a working wire.
When you pull a plug wire and the engine sounds the same, there's your miss.
Coil pack problems usually cause misses to come in pairs, so if you've got two cylinders that are missing then it could be a coil going bad.
It could still be fuel injectors.

Are you mechanical at all? Do you have a Helms manual?
We can help you figure this out, but it does take a little basic knowledge of engines.

TomC
'90ZR1 #792

Lawdawg · 03-01-2007

Thanks for all of the information so far. I have since checked all of the plugs, connections, and fittings and have found no issues. The car is a 1991, so problems with injectors along with fuel/injector cleaner alcohol content seems like a possible culprit.

The condition seems to really present itself when the motor is cold and not up to temp. The problem is when the sputtering or bogging stops, the flywheel rattle continues at idle or when you shut her down.

I dont know, maybe a fuel pump or filter?

I dont have a scaner, but I will attempt to do a spark test next. I should have paid attention in shop class when I was younger, I'm not certain I even know what I'm looking for. Sorry guys, I just like to drive fast!

Z-Factor, do me a favor and check with your contact in Miami about him being able to take a look at it. I had planned to take it to Roger at Horsepower Sales in Pompano for a fidanza, ceramic clutch, and 3:91s, but wonder if I should wait to have this issue resolved first.

Z Factor · 03-02-2007

Quote:

Originally Posted by Lawdawg

Z-Factor, do me a favor and check with your contact in Miami about him being able to take a look at it.

As I suspected he has about a months worth of work going now, but he said he would try to help you out.

PM on the way.

Quote:

Originally Posted by Lawdawg

but wonder if I should wait to have this issue resolved first

If you have confidence they can diagnose and fix your issue/s along with the other work then go for it, but I would not have them do different work while it is running poorly until you get your primary problem fixed first.

03-01-2007	#1
Z Factor Join Date: Dec 2003 Location: S. Florida Posts: 2,647	Re: Did fuel injector cleaner cause problem? Well it could be more than one issue but you would not be the first person to dump fuel injector cleaner into a ZR-1 and experience problems as a result. However the good news is that your concern about the flywheel is probably unfounded as a poor running LT5 can cause it to sound bad. As to a Chevy dealer being able to properly diagnosis the problem, I'd say it is possible but unlikely. My guess is that you will need to replace the injectors, but before you do anything you need to have a knowledgeable person look at it. Aaron would be an excellent choice, but of course he is a decent distance away. I'd call him and see what his thoughts are. There is a guy down in Miami that is very good, but I do not know if he has the time since he is so busy. . I can check with him for you and see what his schedule is like, so just let me know.

03-01-2007	#2
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Did fuel injector cleaner cause problem? L'dawg, When you checked the MAP sensor you checked the electrical plug or you checked the plug and the hose? The issue could be just coincidence although injector snake oil stuff is not advised...only the Techron stuff from Chevron I was told by a GM tech that that is what GM sells over the parts counter in a rebox. Ya gotta pull the SES DTC(trouble code) & post up, or look it up if ya have a FSM(by Helm). If ya have or know some one with a scan tool with the correct software pkg for your yr Z you could run a scan and compare your data to the data in the Helm FSM. Section 6E, "Emissions and Driveability" chapter is where the codes are listed and the section has a page with what the scan data of a normal LT5 looks like in closed loop. Usually he early 90 thru 92(?) injectors are the most problematic...they were designed before the ethanol was added to the fuel. So if you're in that group then the injectors are a prime suspect. The later cars seem to be less susceptable to the ethanol. Only thing with failing/failed injectors: the effects don't go away off idle....they can cause a miss but it's permanent till r & r is done. There are two modes of inj failure: coil shorts and nozzle junk. Shorts cause a non firing = lean cylinder. Junk can be either lean or rich because the junk disturbes the spray pattern....neither condition will necessarily set a "code" (DTC) because the injectors are monitored indirectly by the ECM...via the O2 sensors mostly. The thing is if your miss is real & only at or just off idle speed then I would ask if it gets worse as the car gets to proper coolant temp? It's kind of okay when stone cold? It's there when cold but gets worse as she warms up? All those point to injector coil shorting....in that scenario the injector's short will get worse the more heat gets to the coil and that's the give-away to shorted coils, the miss doesn't go away rather it gets worse. If it is injectors it will get much worse as time passes...the miss that is. I would also do some looking at all your vacuum connections and pull the plugs for inspection, oh and do a spark test while you're there. The more you can eliminate in the absence of a scan tool the further all of us might have some ideas to pass along. The scan makes it easy but diagnostics can be done without one....it's just back to basics. Ya know does it smell rich or lean, the fuel filter is new, the PCV's are good, the vac connections are all in place & there is no sucking noises, Your vac gauge says it's not lean or rich. You get the idea, right? Oh, yea the spark test will help you eliminate the wires and coils...ya know pull one at a time when shes at idle? Sorry to be so long winded about this! Good luck & post up! Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member Last edited by tomtom72; 03-01-2007 at 06:45 AM.

03-01-2007	#3
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,663	Re: Did fuel injector cleaner cause problem? If your Z is a 90-92 most probable cause is fuel injectors. Been there, done that. If your Z is a 93-95, could be plugs, wires, coils. Start and warm up your car until in closed loop. Pull the plug wires carefully one at a time and listen to the sound of engine. The engine should stumble and miss and sound different when you pull a working wire. When you pull a plug wire and the engine sounds the same, there's your miss. Coil pack problems usually cause misses to come in pairs, so if you've got two cylinders that are missing then it could be a coil going bad. It could still be fuel injectors. Are you mechanical at all? Do you have a Helms manual? We can help you figure this out, but it does take a little basic knowledge of engines. TomC '90ZR1 #792

03-01-2007	#4
Lawdawg Join Date: Jan 2007 Location: WPB Florida Posts: 10	Re: Did fuel injector cleaner cause problem? Thanks for all of the information so far. I have since checked all of the plugs, connections, and fittings and have found no issues. The car is a 1991, so problems with injectors along with fuel/injector cleaner alcohol content seems like a possible culprit. The condition seems to really present itself when the motor is cold and not up to temp. The problem is when the sputtering or bogging stops, the flywheel rattle continues at idle or when you shut her down. I dont know, maybe a fuel pump or filter? I dont have a scaner, but I will attempt to do a spark test next. I should have paid attention in shop class when I was younger, I'm not certain I even know what I'm looking for. Sorry guys, I just like to drive fast! Z-Factor, do me a favor and check with your contact in Miami about him being able to take a look at it. I had planned to take it to Roger at Horsepower Sales in Pompano for a fidanza, ceramic clutch, and 3:91s, but wonder if I should wait to have this issue resolved first.