help with code 55
Thread Starter
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
help with code 55
From: bachirzr1@yahoo.com
Subject: i need help code 55 engine
Dear sir
i m Bachar from lebanon my 90 zr1 has a problem i cant start the engine normaly only but with pushing and its run too bad also i have service engine code 55 that is ( Fuel Monitor Lean ) i checked the injectors and the fuel pumps it work great
please informe if you have any idea for this problem because no testing for this code in my service manual
thanks
waiting your reply
Subject: i need help code 55 engine
Dear sir
i m Bachar from lebanon my 90 zr1 has a problem i cant start the engine normaly only but with pushing and its run too bad also i have service engine code 55 that is ( Fuel Monitor Lean ) i checked the injectors and the fuel pumps it work great
please informe if you have any idea for this problem because no testing for this code in my service manual
thanks
waiting your reply
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
Yeah, he's right. Weird. It goes from 54 to 62... 
This is from the LT5 Fuel and Emissions coursebook:
Code 55:
"Fuel Lean Monitor"
Circuit Description:
Whenever the secondary port throttle valves are commanded open, the eight secondary port throttle injectors are added to the sequential primary injectors. If the ECM senses a lean exhaust condition during secondary throttle opening from either the right or left oxygen sensory, a Code 55 sets. Code 55 sets very quickly to avoid any converter damage and to signal the ECM to shut-off secondary operation.
Possible Causes for Code 55:
1. Secondary ignition insulation fault.
2. Lean injector.
3. Inlet filter restriction to injector.
Test Conditions:
1. Secondary fuel pump commanded "ON".
2. Closed loop.
3. Power enrichment mode is enabled.
4. Left or right oxygen indicated lean for two seconds.
Default Action Taken:
1. S.E.S light illuminated.
2. Secondary port throttle disabled.
3. Secondary injectors disabled.
4. Code 55 stored in memory.
This is from the LT5 Fuel and Emissions coursebook:
Code 55:
"Fuel Lean Monitor"
Circuit Description:
Whenever the secondary port throttle valves are commanded open, the eight secondary port throttle injectors are added to the sequential primary injectors. If the ECM senses a lean exhaust condition during secondary throttle opening from either the right or left oxygen sensory, a Code 55 sets. Code 55 sets very quickly to avoid any converter damage and to signal the ECM to shut-off secondary operation.
Possible Causes for Code 55:
1. Secondary ignition insulation fault.
2. Lean injector.
3. Inlet filter restriction to injector.
Test Conditions:
1. Secondary fuel pump commanded "ON".
2. Closed loop.
3. Power enrichment mode is enabled.
4. Left or right oxygen indicated lean for two seconds.
Default Action Taken:
1. S.E.S light illuminated.
2. Secondary port throttle disabled.
3. Secondary injectors disabled.
4. Code 55 stored in memory.
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
need help code 55
i m bachir
thanks for your reply good information but my car steel have the problem the engine crank but not working i checked before the feul pumps pressure on car the both working and give about 52 psi
i sent the injectors to clean and test out of the car they all working i replace the o ring i replace the coils the spurk plugs there is electricale in wires
when the problem begin i could turn the engine so hard take long time
and engine run little bad but now i can start the engine with full batery i can only with pushing and engine run so bad the code flash in high rpm and the problem still without full power off
what should i check againe please informe
thanks againe
thanks for your reply good information but my car steel have the problem the engine crank but not working i checked before the feul pumps pressure on car the both working and give about 52 psi
i sent the injectors to clean and test out of the car they all working i replace the o ring i replace the coils the spurk plugs there is electricale in wires
when the problem begin i could turn the engine so hard take long time
and engine run little bad but now i can start the engine with full batery i can only with pushing and engine run so bad the code flash in high rpm and the problem still without full power off
what should i check againe please informe
thanks againe
Burning Brakes
Joined: May 2007
Posts: 965
Likes: 13
From: turn 12 at Road America or TX
i m bachir
thanks for your reply good information but my car steel have the problem the engine crank but not working i checked before the feul pumps pressure on car the both working and give about 52 psi
i sent the injectors to clean and test out of the car they all working i replace the o ring i replace the coils the spurk plugs there is electricale in wires
when the problem begin i could turn the engine so hard take long time
and engine run little bad but now i can start the engine with full batery i can only with pushing and engine run so bad the code flash in high rpm and the problem still without full power off
what should i check againe please informe
thanks againe
thanks for your reply good information but my car steel have the problem the engine crank but not working i checked before the feul pumps pressure on car the both working and give about 52 psi
i sent the injectors to clean and test out of the car they all working i replace the o ring i replace the coils the spurk plugs there is electricale in wires
when the problem begin i could turn the engine so hard take long time
and engine run little bad but now i can start the engine with full batery i can only with pushing and engine run so bad the code flash in high rpm and the problem still without full power off
what should i check againe please informe
thanks againe
to the explanation above, 55 should not appear unless the engine is
running with the secondaries open which should not be happening
on cold startup. I don't have a manual available to me now so
I'm wondering if the training information is correct.
Going back in time, has the car ever operated properly? Are there
any events that may have caused this problem?
Racer
Joined: Aug 2001
Posts: 370
Likes: 0
i m bachir
thanks for your reply good information but my car steel have the problem the engine crank but not working i checked before the feul pumps pressure on car the both working and give about 52 psi
i sent the injectors to clean and test out of the car they all working i replace the o ring i replace the coils the spurk plugs there is electricale in wires
when the problem begin i could turn the engine so hard take long time
and engine run little bad but now i can start the engine with full batery i can only with pushing and engine run so bad the code flash in high rpm and the problem still without full power off
what should i check againe please informe
thanks againe
thanks for your reply good information but my car steel have the problem the engine crank but not working i checked before the feul pumps pressure on car the both working and give about 52 psi
i sent the injectors to clean and test out of the car they all working i replace the o ring i replace the coils the spurk plugs there is electricale in wires
when the problem begin i could turn the engine so hard take long time
and engine run little bad but now i can start the engine with full batery i can only with pushing and engine run so bad the code flash in high rpm and the problem still without full power off
what should i check againe please informe
thanks againe
is to change the fuel filter,that should take car of the code 55 for you.
AL.
Last edited by BERTZR1; Aug 8, 2007 at 11:39 AM.
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
need help code 55
the problem begin before im going to gas station the fuel was too low in tank and engine run bad and still run bad after put the feul but its still run the next day but now no start and run more bad im going to replace the filter
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
The fact that it won't start, or is hard to start, probably isn't related to the code 55. It sounds like there is something more significant wrong. Hopefully it's just a really clogged fuel filter.
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
need help code 55
Hi I m Bachir i need your help
i changed the filter the engine run little better but no way to start engine normally this time i spray a cleaner from the intake the engine start quickly with the spray what should i check for this trouble i want to know if the spurk wires make this trouble like this suddenly and about the fuel pumps i checked the pressure is it OK or i have check other things because i feel like it fuel problem please help me in some info
thanks
i changed the filter the engine run little better but no way to start engine normally this time i spray a cleaner from the intake the engine start quickly with the spray what should i check for this trouble i want to know if the spurk wires make this trouble like this suddenly and about the fuel pumps i checked the pressure is it OK or i have check other things because i feel like it fuel problem please help me in some info
thanks
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Melting Slicks
Joined: Oct 2004
Posts: 2,283
Likes: 0
From: Leeds Alabama
I DO NOT recommend spraying fluid into the intake. Did the car backfire recently like maybe when it was running out of fuel. My bet is that running it low on gas ruined an already old fuel pump or clogged up the fuel system with debris from bottom of fuel tank. It could be anywhere from the pumps to the injectors. When you run a car out of gas, it picks up every little bit of trash with the last fuel to try to stay running. You may have multiple problems Fuel pump/ Fuel filter , fuel filter / clogged injectors / Clogged injectors / trash in the secondaries. These cars do NOT like to be low on gas!
Melting Slicks
Joined: May 2001
Posts: 2,159
Likes: 64
From: Nichols Florida
Try to start the car for 10-20 sec. Pull the plugs and look to see if they are wet with gas. If they are dry and you have good fuel pressure, you have bad injectors. You can check them by pulling the plenum. Lift the fuel rail up so you can see the injectors spray. You can then disconnect the injector leads for the primary injectors. Make a pigtail that you can use to pulse the injectors in place. Crank the engine to pressure the fuel rail then pulse the injectors to see the spray pattern for each injector. You can also pull the injectors and pulse them with 12 volt and you should hear them click.
Be careful once you pressure the fuel rail pulling an injector will spray fuel all over the place. Ask me how I know.(LOL)
Tyler
Be careful once you pressure the fuel rail pulling an injector will spray fuel all over the place. Ask me how I know.(LOL)
Tyler
Navigator
Joined: Jun 2007
Posts: 9
Likes: 0
From: Edmonton Alberta
Or it could be that the injecotrs are not working. If they all tested
o.k. when you had them out, it might be electrical. Possably ECM/PCM
You can chekc to see if the injectors are being turned on by the ECM
by checking them with a NODE light if you have access, or a simple
test light across the terminals for the injectors.
If the car started easy when you sprayed down the intake, then is
is definatly fuel related, Ignition system is working o.k.
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
need help code 55
thanks for your information
today i remouved the pleneum and i leave all wires conected in ignition module i checked the electricle signal one two injectors by test light when i try to start the engine there is no signal at all please help what should i check
morover the things i can undrestand wy the engine stay run whe start the engine with spray from intake but bad and shut down if i leave the gas pedal
morover the problem when begin the engine run bad and start but to hard or with pushing the car on second gear not like now no way to start without spray
please informe with your information
today i remouved the pleneum and i leave all wires conected in ignition module i checked the electricle signal one two injectors by test light when i try to start the engine there is no signal at all please help what should i check
morover the things i can undrestand wy the engine stay run whe start the engine with spray from intake but bad and shut down if i leave the gas pedal
morover the problem when begin the engine run bad and start but to hard or with pushing the car on second gear not like now no way to start without spray
please informe with your information
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
I really don't think Code 55 is your problem. That's only when the secondaries are active. Your car won't even start up.
If it cranks over healthy, then you would seem to clearly have either an air, fuel, or spark problem. I don't think anyone is going to be able to tell you which it is without looking at the car. If it runs when you spray stuff in the motor, it sounds like it's probably a fuel problem.
If it were my car, I sure wouldn't rev it up to 6,000 rpm if it were running like that.
Presumably you had a test light on the primary injectors, right? If it's just a regular test light, I don't know if that would even work, as the injectors are only on for milliseconds at a time.
If it cranks over healthy, then you would seem to clearly have either an air, fuel, or spark problem. I don't think anyone is going to be able to tell you which it is without looking at the car. If it runs when you spray stuff in the motor, it sounds like it's probably a fuel problem.
If it were my car, I sure wouldn't rev it up to 6,000 rpm if it were running like that.
Presumably you had a test light on the primary injectors, right? If it's just a regular test light, I don't know if that would even work, as the injectors are only on for milliseconds at a time.
Navigator
Joined: Jun 2007
Posts: 9
Likes: 0
From: Edmonton Alberta
If the engine runs up to 6000 rpm after you start it with spray,
then it should be getting fuel. It would not run that high on spray
alone. Secondly you know you have spark if it runs.
Maybe there is a bad vacuum leak causing the engine not to
idle, and run properly.
Did the engine have a bad backfire when the problem started?
I would reccomend pulling the spark plugs to see what they look like,
and then if you can get the tools to do a leakdown on the cylinders,
that would give you an idea of the mechanical condition of the engine.
then it should be getting fuel. It would not run that high on spray
alone. Secondly you know you have spark if it runs.
Maybe there is a bad vacuum leak causing the engine not to
idle, and run properly.
Did the engine have a bad backfire when the problem started?
I would reccomend pulling the spark plugs to see what they look like,
and then if you can get the tools to do a leakdown on the cylinders,
that would give you an idea of the mechanical condition of the engine.
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
hi
after start the engine with a cleaner spray from intake i don't need the spray more after start to get high rpm i can use the pedal that's mean the that the injector working after start with load gas pedal that's mean the fuse is OK
the question is could the damage of ecm control in the injector be only on the start level only without damage the all system ( never spray injector ) does the both solid relay make like that problem ? moreover i read in manual that is code 55 of service engine only come when the full power on mode i had the code with car stop and full power off that's why i need to know and take sure how can check the order controller come from ecm to injector
moreover many zr1owner don't believe me that's i have code 55 without the secondary system and car stop wiyh run bad engine
thanks waiting your reply
after start the engine with a cleaner spray from intake i don't need the spray more after start to get high rpm i can use the pedal that's mean the that the injector working after start with load gas pedal that's mean the fuse is OK
the question is could the damage of ecm control in the injector be only on the start level only without damage the all system ( never spray injector ) does the both solid relay make like that problem ? moreover i read in manual that is code 55 of service engine only come when the full power on mode i had the code with car stop and full power off that's why i need to know and take sure how can check the order controller come from ecm to injector
moreover many zr1owner don't believe me that's i have code 55 without the secondary system and car stop wiyh run bad engine
thanks waiting your reply
Racer
Joined: Jun 2006
Posts: 392
Likes: 0
From: lost wages , nev
ok disconnect your battery for a couple of minutes to wipe out all your trouble codes then start the car again and see what trouble codes come up. you can ck for vaccume leaks by using a propane torch with a 2 ft rubber hose attached start the car and turnon the popane (dont light it ever) wh and if you find a vaccume the rpm will rise up .also ck to see if the map sensor hose has come off or is deteriorated. hope this helps
Navigator
Joined: Jun 2007
Posts: 9
Likes: 0
From: Edmonton Alberta
ok disconnect your battery for a couple of minutes to wipe out all your trouble codes then start the car again and see what trouble codes come up. you can ck for vaccume leaks by using a propane torch with a 2 ft rubber hose attached start the car and turnon the popane (dont light it ever) wh and if you find a vaccume the rpm will rise up .also ck to see if the map sensor hose has come off or is deteriorated. hope this helps
with a scanner. Is the throttle closing all the way, sounds like the engine is getting too much air at idle.
Not that familiar with these engines yet, does anyone know if it is possable that the secondary air valves in the intake are stuck open?
Might be related to code 55? Possable causing it to lean out too much.
Not sure if this make sense, as the IAC should limit the air in the intake,
but like is said i'n not familiar with all the intricacies of this engine yet.
Still leaning towards a vacuum leak or a sensor.
Racer
Joined: Jun 2006
Posts: 392
Likes: 0
From: lost wages , nev
there is a set of secondary butterflies that are vaccume operated. guess they could stick . only way to tell for sure is pull the plenum. if the car sat for a long time maybe rust or worse abolt holding them open . but i have never heard of that happening . but therew is a first ime for everything . i think basir needs to give us a history lesson on this car . think that might help.
Advanced
Joined: Aug 2007
Posts: 62
Likes: 0
need help code 55
hi
dear Albert
today i checked the fuel pump fuse and the injector fuse all is working and the hot wire to ground on injectors but no puls from any injector coming from ecm wile crank to start are u sure that i can see the noid light flashing
moreover if a problem in control from ecm the engine should not run after start engine with spray with the gas pedal or its possible?
i just ask if you have the test manual to know where is the problem
thanks
dear Albert
today i checked the fuel pump fuse and the injector fuse all is working and the hot wire to ground on injectors but no puls from any injector coming from ecm wile crank to start are u sure that i can see the noid light flashing
moreover if a problem in control from ecm the engine should not run after start engine with spray with the gas pedal or its possible?
i just ask if you have the test manual to know where is the problem
thanks