1988 300TE - Misfires - Where to go now?
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Now we're getting somewhere. Cross off injectors and ignition related issues. It sounds like a vacuum leak of some kind. I'm not sure what's missing in your pic, but that doesn't look like a vacuum hose to me so I don't think that's your problem. I would check injector seals next. Spray WD-40 around each injector while it's running and listen for a change. Look everywhere for a vacuum hose leak. There should be a diagram under the hood. Trace each line and look for cracks or disconnected hoses and tubes. Remember to check the transmission modulator and brake booster lines.
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1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Ok I sprayed WD-40 around each injector and there was no change at all. While I down there I also cleaned the HT electrical points as the Haynes manual suggested that. I carefully looked at each line coming out from the injectors for any imperfections at all and they all looked good.
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A faster technique for finding intake manifold vacuum leaks is to get a bottle of propane and attach a length of rubber hose to the gas valve. Open the valve so you have a steady flow of gas. Then hold the hose near suspected leak points while the engine is idling. If there is a leak, propane will be siphoned in through the leak. The resulting "correction" in the engine's air/fuel ratio should cause a noticeable change in idle speed and/or smoothness (Note: on engines with computerized idle speed control, disconnect the idle speed control motor first)
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1994 E320 Dragon Wagon
"Ok I sprayed WD-40 around each injector"...
I'm not sure if WD-40 will work as well as starting fluid for leak testing. The idle will pick-up immediately if it sucks in a whiff of fluid. WD is a lubricant and solvent which may be as combustible (I've never tried it). If the intent was to temporarily seal a leak gap with WD's oil property, it may not be as effective.
I'm not sure if WD-40 will work as well as starting fluid for leak testing. The idle will pick-up immediately if it sucks in a whiff of fluid. WD is a lubricant and solvent which may be as combustible (I've never tried it). If the intent was to temporarily seal a leak gap with WD's oil property, it may not be as effective.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
"Ok I sprayed WD-40 around each injector"...
I'm not sure if WD-40 will work as well as starting fluid for leak testing. The idle will pick-up immediately if it sucks in a whiff of fluid. WD is a lubricant and solvent which may be as combustible (I've never tried it). If the intent was to temporarily seal a leak gap with WD's oil property, it may not be as effective.
I'm not sure if WD-40 will work as well as starting fluid for leak testing. The idle will pick-up immediately if it sucks in a whiff of fluid. WD is a lubricant and solvent which may be as combustible (I've never tried it). If the intent was to temporarily seal a leak gap with WD's oil property, it may not be as effective.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
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Mixture maybe its referred to. It's how you set the injectors to take in so much fuel. Well we set it to 30/70 or 70/30 we weren't sure which one was the rich or lean but the car seemed to feel nicer with it set to this rather than the 50/50. So I will drive it for a full tank, see how it runs and go from there.
As for the smell, my dad smelt the exhaust and said it doesn't smell more of gas than any other car.
The misfires are definitely random and temperamental as when I left today it was small misfires, then stopping at lights it was misfiring alot harder, then right before doing the Duty Cycle/Mixture it was back to mediocre misfires again.
What's next on the list to test?
As for the smell, my dad smelt the exhaust and said it doesn't smell more of gas than any other car.
The misfires are definitely random and temperamental as when I left today it was small misfires, then stopping at lights it was misfiring alot harder, then right before doing the Duty Cycle/Mixture it was back to mediocre misfires again.
What's next on the list to test?
Last edited by ps2cho; Sep 16, 2007 at 08:21 PM.
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Hi guys, I'm back...been really busy with school.
Bumping the thread...I'm getting really anxious about getting this fixed.
Should I just go and pay someone to diagnose it for me? Can anybody even do that? Is it expensive?
Bumping the thread...I'm getting really anxious about getting this fixed.
Should I just go and pay someone to diagnose it for me? Can anybody even do that? Is it expensive?
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From: Long Beach, Ca
lots of cars
Have you ever checked the temp sensor? The two post sensor at the rear of the engine.
I can think of three things that can cause this...
Temp Sensor ( Not green with 3 post)
EHA Valve
Fuel Distributor
Also try cleaning the idle control valve and see if it works...
I can think of three things that can cause this...
Temp Sensor ( Not green with 3 post)
EHA Valve
Fuel Distributor
Also try cleaning the idle control valve and see if it works...
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Thanks for the suggestions though! I really appreciate it.
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From: Boston
is a German Tank
I REALLY wanna know what you uncover.
Oddly enough, my car has been doing the SAME EXACT thing as yours.
I replace the plugs and 300-500 miles later, replace again.
Mine has been on cyl, # 3 though....and does not run like crap
i'm all ears!
Oddly enough, my car has been doing the SAME EXACT thing as yours.
I replace the plugs and 300-500 miles later, replace again.
Mine has been on cyl, # 3 though....and does not run like crap
i'm all ears!
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As for yours, have you checked the High tension leads?
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is a German Tank
only on one cylinder?
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What if they can't diagnose it? Do I still generally have to pay them? I guess at least they can tell me what it isnt...
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ps2cho, I'd be sure to outline exactly what you've done to the car so far so they don't spend hours rechecking the stuff you've already checked (unless you want them to doublecheck your work)
Unless they've got a couple of ideas right off the bat, I'd be afraid you'll be paying them to go through all the same stuff you've already gone through. Could get pricey.
PS, my '73 220D shook like nobody's business at idle when I got it, felt like the motor was going to come apart. Ended up swapping out the motor mounts and it smoothed out nicely. I've never heard of motor mounts being a problem on a gas motor though, and your car has such low miles.
Unless they've got a couple of ideas right off the bat, I'd be afraid you'll be paying them to go through all the same stuff you've already gone through. Could get pricey.
PS, my '73 220D shook like nobody's business at idle when I got it, felt like the motor was going to come apart. Ended up swapping out the motor mounts and it smoothed out nicely. I've never heard of motor mounts being a problem on a gas motor though, and your car has such low miles.
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ps2cho, I'd be sure to outline exactly what you've done to the car so far so they don't spend hours rechecking the stuff you've already checked (unless you want them to doublecheck your work)
Unless they've got a couple of ideas right off the bat, I'd be afraid you'll be paying them to go through all the same stuff you've already gone through. Could get pricey.
PS, my '73 220D shook like nobody's business at idle when I got it, felt like the motor was going to come apart. Ended up swapping out the motor mounts and it smoothed out nicely. I've never heard of motor mounts being a problem on a gas motor though, and your car has such low miles.
Unless they've got a couple of ideas right off the bat, I'd be afraid you'll be paying them to go through all the same stuff you've already gone through. Could get pricey.
PS, my '73 220D shook like nobody's business at idle when I got it, felt like the motor was going to come apart. Ended up swapping out the motor mounts and it smoothed out nicely. I've never heard of motor mounts being a problem on a gas motor though, and your car has such low miles.
But yes I plan to tell him the things that I have personally done. I won't include the stuff the previous owners said because I can't afford to have it skipped over if they had it done improperly or anything.
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is a German Tank
I also thought about the mounts, but it's not because if it were, the "misfires" would be constant and not variable and they are VERY variable. Some days I can hardly feel it and others its like an earthquake happening in the car. It's totally inconsistent.
But yes I plan to tell him the things that I have personally done. I won't include the stuff the previous owners said because I can't afford to have it skipped over if they had it done improperly or anything.
But yes I plan to tell him the things that I have personally done. I won't include the stuff the previous owners said because I can't afford to have it skipped over if they had it done improperly or anything.
and yes sir I can feel it inside my car! It's weird...I've never felt a shiver in my car before, she's starting to show her age
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Ok got it looked at by the local Benz shop...He first adjusted the mixture to the exact place where it should be...He drove it around but ended up not being exact as to where the problem lies.
He put on the notes:
-Test engine found fuel mix to rich
-Adjust fuel mix found kick down
-Cable strut clean and lube cable
-Found rust at Fuel Distributor
-Possible rust inside gas tank
He said in his professional opinion, I should just leave the car alone as it drives fine...it's just the idle that is irratic. But honestly I'm not driving a car that shakes this hard when I pull up to every light.
So you guys think that I should find a nice looking used fuel distributor and replace that first? As for the gas tank, my dad said he can take it into his work and get all the rust off for relatively cheap. He said to get it fixed would be costly as there are alot of parts that could have rust in them...including the pistons (I think he said).
One thing he did while the car was running though...He unscrewed the screws to the Fuel Injectors a little and fluid came out (I am assuming thats the gasoline? Sorry noob)...why did he loosen them? He also was spraying brake cleaner all around the injector lines (I am assuming to check for leaks correct?)
I wonder if I will ever get this fixed...
He put on the notes:
-Test engine found fuel mix to rich
-Adjust fuel mix found kick down
-Cable strut clean and lube cable
-Found rust at Fuel Distributor
-Possible rust inside gas tank
He said in his professional opinion, I should just leave the car alone as it drives fine...it's just the idle that is irratic. But honestly I'm not driving a car that shakes this hard when I pull up to every light.
So you guys think that I should find a nice looking used fuel distributor and replace that first? As for the gas tank, my dad said he can take it into his work and get all the rust off for relatively cheap. He said to get it fixed would be costly as there are alot of parts that could have rust in them...including the pistons (I think he said).
One thing he did while the car was running though...He unscrewed the screws to the Fuel Injectors a little and fluid came out (I am assuming thats the gasoline? Sorry noob)...why did he loosen them? He also was spraying brake cleaner all around the injector lines (I am assuming to check for leaks correct?)
I wonder if I will ever get this fixed...
Last edited by ps2cho; Nov 7, 2007 at 06:23 PM.
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What kind of gas grade do you use? Did he use any electronic device to adjust the fuel mixture when he was moving the fuel distributor screw? If he didn't then it's not 100% correct. Also check that the cold start injector is not leaking because if it does then that will be the source of your misfire.
I would still check the EHA valve and replace it with a used one. Also check that temp sensor because when i replaced mine my car was really smooth after having a misfire like yours. It's kinda hard to diagnose a problem on the w124 but you should learn what every part does and start with the fuel system. I also had a problem with the fuel pump relay where it would cut off and come back on making my car stall a little so it felt like a misfire.
I would still check the EHA valve and replace it with a used one. Also check that temp sensor because when i replaced mine my car was really smooth after having a misfire like yours. It's kinda hard to diagnose a problem on the w124 but you should learn what every part does and start with the fuel system. I also had a problem with the fuel pump relay where it would cut off and come back on making my car stall a little so it felt like a misfire.
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What kind of gas grade do you use? Did he use any electronic device to adjust the fuel mixture when he was moving the fuel distributor screw? If he didn't then it's not 100% correct. Also check that the cold start injector is not leaking because if it does then that will be the source of your misfire.
I would still check the EHA valve and replace it with a used one. Also check that temp sensor because when i replaced mine my car was really smooth after having a misfire like yours. It's kinda hard to diagnose a problem on the w124 but you should learn what every part does and start with the fuel system. I also had a problem with the fuel pump relay where it would cut off and come back on making my car stall a little so it felt like a misfire.
I would still check the EHA valve and replace it with a used one. Also check that temp sensor because when i replaced mine my car was really smooth after having a misfire like yours. It's kinda hard to diagnose a problem on the w124 but you should learn what every part does and start with the fuel system. I also had a problem with the fuel pump relay where it would cut off and come back on making my car stall a little so it felt like a misfire.
He just moved it with a screw...but he was probably closer than we were...We just guessed using a multimeter...We didn't know which one was Lean or Rich...just went off what the engine seemed to respond with.
Also..I figure I bought the car for $3,000 which was a steal...so I have some of the car's actual value in cash right now. I will be keeping this car within the family...so as long as I can afford the fixes, it won't be money that will be passed on to some random guy. I am planning on keeping this for myself til the engine finally gives up! (I'm SURE that won't be be long considering the condition of the engine inside as shown at the top of the thread!)
Last edited by ps2cho; Nov 7, 2007 at 07:13 PM.
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E-ZGO 53hp., 1999 E 430 sport, 2004 E 55, 2008 Tahoe LTZ on 24"s
Hi guys,
I made a thread over at the mercedesshop forum and it got to 4 pages long and now there is almost no responses so I decided to try here.
I will sum up the problem and everything we have done so you don't have to go through the entire thread.
Firstly, the car is a 1988 300TE with 65k miles on it when I bought it ($3000!) and it would stall randomly and misfire hard. Here are pictures of the spark plugs every 300-400 miles:
First we did a compression test and these were the results:
We next put 20/50 oil into the engine and it leaked less. (it was using a quart of oil every 500 miles)
Next we changed the duty cycle to 45-50% and replaced the OVP which fixed the stalling problem.
Then we replaced the Voltage Regulator.
Finally got round to doing the Valve Stem Seals at 72,000 on the car:
^ As you can see the engine is in amazing condition.
This solved the oil leaks onto the spark plugs and now it does not use a drop of oil at all through the 3000 miles before I get an oil change.
Next we replaced the Ignition Leads as they were certainly making less than stellar spark's with new Bosch leads which helped the misfire A LOT! It is STILL there though.
Lastly, we replaced the resistor style spark plugs with new Bosch NON-Resistor spark plugs like the car is supposed to have. I couldn't notice a difference in the misfires.
What is our next course of action to fix this horrible never ending problem?
The previous owners said they replaced the O2 sensor 6 months before we bought the car, but could it have gotten contaminated through the oil leaks we had?
What else could be the problem here?
Any help would be very appreciated!!!
Thanks, ps2cho
I made a thread over at the mercedesshop forum and it got to 4 pages long and now there is almost no responses so I decided to try here.
I will sum up the problem and everything we have done so you don't have to go through the entire thread.
Firstly, the car is a 1988 300TE with 65k miles on it when I bought it ($3000!) and it would stall randomly and misfire hard. Here are pictures of the spark plugs every 300-400 miles:
First we did a compression test and these were the results:
We next put 20/50 oil into the engine and it leaked less. (it was using a quart of oil every 500 miles)
Next we changed the duty cycle to 45-50% and replaced the OVP which fixed the stalling problem.
Then we replaced the Voltage Regulator.
Finally got round to doing the Valve Stem Seals at 72,000 on the car:
^ As you can see the engine is in amazing condition.
This solved the oil leaks onto the spark plugs and now it does not use a drop of oil at all through the 3000 miles before I get an oil change.
Next we replaced the Ignition Leads as they were certainly making less than stellar spark's with new Bosch leads which helped the misfire A LOT! It is STILL there though.
Lastly, we replaced the resistor style spark plugs with new Bosch NON-Resistor spark plugs like the car is supposed to have. I couldn't notice a difference in the misfires.
What is our next course of action to fix this horrible never ending problem?
The previous owners said they replaced the O2 sensor 6 months before we bought the car, but could it have gotten contaminated through the oil leaks we had?
What else could be the problem here?
Any help would be very appreciated!!!
Thanks, ps2cho
It looks to me like your car has massive contamination in your fuel system.
1. Remove and tumble clean fuel tank (what comes out will shock you)
2. Replace fuel filters.
3. Blow out fuel lines and check evap lines, check gas cap too.
4. Fill up with Chevron gas and add 2x recommended techron, drive for 500
highway miles.
5. Replace O2 sensor, adjust idle mixture on CIS with freq valve
disconnected. change oil and continue to use chevron gas.
At some time in your cars 20 year history someone put something in the tank that was not gasoline.
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It looks to me like your car has massive contamination in your fuel system.
1. Remove and tumble clean fuel tank (what comes out will shock you)
2. Replace fuel filters.
3. Blow out fuel lines and check evap lines, check gas cap too.
4. Fill up with Chevron gas and add 2x recommended techron, drive for 500
highway miles.
5. Replace O2 sensor, adjust idle mixture on CIS with freq valve
disconnected. change oil and continue to use chevron gas.
At some time in your cars 20 year history someone put something in the tank that was not gasoline.
1. Remove and tumble clean fuel tank (what comes out will shock you)
2. Replace fuel filters.
3. Blow out fuel lines and check evap lines, check gas cap too.
4. Fill up with Chevron gas and add 2x recommended techron, drive for 500
highway miles.
5. Replace O2 sensor, adjust idle mixture on CIS with freq valve
disconnected. change oil and continue to use chevron gas.
At some time in your cars 20 year history someone put something in the tank that was not gasoline.
