1988 300TE - Misfires - Part #2


It's kinda funny dude, the V-leak has been the most prolific and repeated response since your first post across a couple fan sites. Doh! Not rubbing salt here, I really hate this kinda stuff when it happens to me.
It's kinda funny dude, the V-leak has been the most prolific and repeated response since your first post across a couple fan sites. Doh! Not rubbing salt here, I really hate this kinda stuff when it happens to me.
I still might not have one? We won't know until Monday when I take her down to get smoked.


Around here it's duct tape and baling wire or nothing! You wouldn't believe these local repair guys. 

Besides, my car is such a POS I don't even know if I would invest in a oil change. I'd never wash it, either. It's what they call an "island car", which means it barely runs. The whole island is only 26 miles long so if it breaks down it's not a big deal. There are much nicer cars awaiting the crusher, I'm sure.
Last edited by shdoug; Jul 13, 2008 at 09:52 PM.
Around here it's duct tape and baling wire or nothing! You wouldn't believe these local repair guys. 

Besides, my car is such a POS I don't even know if I would invest in a oil change. I'd never wash it, either. It's what they call an "island car", which means it barely runs. The whole island is only 26 miles long so if it breaks down it's not a big deal. There are much nicer cars awaiting the crusher, I'm sure. 
....Its the injectors

Took the car down and the guys was real fast, honest and a cool guy. Franks Foreign Auto Repair at Laguna Beach.
I requested the smoke test and he ran it. No vacuum leaks, but he found that injectors 3+4 were leaking. That makes me so mad because the previous owners had the receipt showing both injectors + seals were replaced

I'm taking the car back down later today when he gets the parts in. I knew there wasn't any vacuum leaks, but as we have stated throughout this thread, it needed to be checked. I can replace the seals myself -- but after all this time I just want to get it over and done with.
He also mentioned that my thermostat housing was leaking....Anybody shed some more light on this? I decided against having him replace it because I read somewhere that its pretty straight forward. Is a leaky thermostat something that I should replace soon? Could it be affecting anything like MPG?
I'm so excited....but better not keep my hopes up as thats what happened last time and it ended up not fixing the problem. I better hopes this time as you can't have leaky injector seals without sure problems....



The Best of Mercedes & AMG
....Its the injectors

Took the car down and the guys was real fast, honest and a cool guy. Franks Foreign Auto Repair at Laguna Beach.
I requested the smoke test and he ran it. No vacuum leaks, but he found that injectors 3+4 were leaking. That makes me so mad because the previous owners had the receipt showing both injectors + seals were replaced

I'm taking the car back down later today when he gets the parts in. I knew there wasn't any vacuum leaks, but as we have stated throughout this thread, it needed to be checked. I can replace the seals myself -- but after all this time I just want to get it over and done with.
He also mentioned that my thermostat housing was leaking....Anybody shed some more light on this? I decided against having him replace it because I read somewhere that its pretty straight forward. Is a leaky thermostat something that I should replace soon? Could it be affecting anything like MPG?
I'm so excited....but better not keep my hopes up as thats what happened last time and it ended up not fixing the problem. I better hopes this time as you can't have leaky injector seals without sure problems....




Count them chickens when they hatch, but sounds like the right tree is finally bieng barked at. Hopefully you found a very competent tech that will be able to help you out in the future. With that thermo housing it isn't very hard and is no major complication to normal operation. just a routine maint. thing.
....Its the injectors

Took the car down and the guys was real fast, honest and a cool guy. Franks Foreign Auto Repair at Laguna Beach.
I requested the smoke test and he ran it. No vacuum leaks, but he found that injectors 3+4 were leaking. That makes me so mad because the previous owners had the receipt showing both injectors + seals were replaced

I'm taking the car back down later today when he gets the parts in. I knew there wasn't any vacuum leaks, but as we have stated throughout this thread, it needed to be checked. I can replace the seals myself -- but after all this time I just want to get it over and done with.
He also mentioned that my thermostat housing was leaking....Anybody shed some more light on this? I decided against having him replace it because I read somewhere that its pretty straight forward. Is a leaky thermostat something that I should replace soon? Could it be affecting anything like MPG?
I'm so excited....but better not keep my hopes up as thats what happened last time and it ended up not fixing the problem. I better hopes this time as you can't have leaky injector seals without sure problems....




Why ???
Because.....There are three types of injector leaks - it can leak fuel into the manifold from the nozzle, it can leak fuel into the engine compartment from the fuel rail, and it can leak air (vacuum leak) from the manifold.
Did he discover the injector seal problem with the smoke?
Curious if his conclusion that it was an injector seal vacuum leak ?
Why ???
Because.....There are three types of injector leaks - it can leak fuel into the manifold from the nozzle, it can leak fuel into the engine compartment from the fuel rail, and it can leak air (vacuum leak) from the manifold.
Did he discover the injector seal problem with the smoke?
Curious if his conclusion that it was an injector seal vacuum leak ?

I am picking the car up within the hour, so I'll double check.
Last edited by ps2cho; Jul 14, 2008 at 06:11 PM.
I still see the rpm's bobbing up and down +-50rpm...
I'm gonna go adjust the mixture and make sure thats fine now that the injectors are functioning fine.
He said that he smoked it after doing the injectors too and everything was perfect. So from here on out -- The TE is vacuum sealed. I called him up on it and he recommended first the mixture, then he mentioned the timing and firing order....Isn't the firing order established only via the rotor/cap/position of wires on the cap....all three which are replaced + in the right position.
About the timing -- I have a gun to test it so what should I be looking for?


I still see the rpm's bobbing up and down +-50rpm...
I'm gonna go adjust the mixture and make sure thats fine now that the injectors are functioning fine.
He said that he smoked it after doing the injectors too and everything was perfect. So from here on out -- The TE is vacuum sealed. I called him up on it and he recommended first the mixture, then he mentioned the timing and firing order....Isn't the firing order established only via the rotor/cap/position of wires on the cap....all three which are replaced + in the right position.
About the timing -- I have a gun to test it so what should I be looking for?
I really don't think timing is an issue, though. Unless the timing chain is loose it shouldn't change. You said: "Isn't the firing order established only via the rotor/cap/position of wires on the cap....all three which are replaced + in the right position." Yes. Pretty hard to screw that up.
Also, if the firing order was off even by 2 cylinders it would run like crap and barely be driveable, so that's not a problem.
I really don't think timing is an issue, though. Unless the timing chain is loose it shouldn't change. You said: "Isn't the firing order established only via the rotor/cap/position of wires on the cap....all three which are replaced + in the right position." Yes. Pretty hard to screw that up.
Also, if the firing order was off even by 2 cylinders it would run like crap and barely be driveable, so that's not a problem.
Ya I figured firing order wasn't an issue....I mean its hard to go wrong when the wires are the appropriate lengths, along with a diagram right on the cap
Ya thats not the problem at all.Now that I have established the fuel injectors are perfectly fine and I have no vacuum leaks anywhere else....maybe I should go back and test the wires next to make sure they are all up to spec. What should be the correct ohms(is that the right specification??) be for each wire?
I still see the rpm's bobbing up and down +-50rpm...
I'm gonna go adjust the mixture and make sure thats fine now that the injectors are functioning fine.
He said that he smoked it after doing the injectors too and everything was perfect. So from here on out -- The TE is vacuum sealed. I called him up on it and he recommended first the mixture, then he mentioned the timing and firing order....Isn't the firing order established only via the rotor/cap/position of wires on the cap....all three which are replaced + in the right position.
About the timing -- I have a gun to test it so what should I be looking for?
What RPM is your idle set?
Use a dwell tach to check your settings.
You've gone this far, so if you want it to run, you need to get back to factory spec.
Looks like a device that I could use in the future too....so I have no problems buying one.
It's a necessity with older cars.
The tach feature is convenient as it's right in front of you as you set your timing.
When you set your timing you need to identify at idle and at full advance which if I recall on the M103 is around 3200 rpm.
Also you can see how the RPM changes as you mess with the air/fuel adjustments.
For $28.00 it'll save a lot of shoe leather running back to see what the tach reads....
It's a necessity with older cars.
The tach feature is convenient as it's right in front of you as you set your timing.
When you set your timing you need to identify at idle and at full advance which if I recall on the M103 is around 3200 rpm.
Also you can see how the RPM changes as you mess with the air/fuel adjustments.
For $28.00 it'll save a lot of shoe leather running back to see what the tach reads....
Will report back in a few days when I get it with any results.
You've had that car probed by other shops right? Someone had to put a scope on that bad-boy looking for timing drift or ignition related missing. That is a straight forward diag. even small-time shops perform with accurate results. I wouldn't go diving into timing until you get a second opinion.
The T-stat leak is just a tired gasket under the housing. Look for a trail or stains of a coolant around the housing. It could simply cause slow loss of coolant but should be corrected.
Buy a new gasket and scrape the old housing and mount surface clean with a putty knife. You can use a gasket sealer, most just assemble dry with the new gasket. Torque evenly and not much over snug. Leak-be-Fixed.
You've had that car probed by other shops right? Someone had to put a scope on that bad-boy looking for timing drift or ignition related missing. That is a straight forward diag. even small-time shops perform with accurate results. I wouldn't go diving into timing until you get a second opinion.
The T-stat leak is just a tired gasket under the housing. Look for a trail or stains of a coolant around the housing. It could simply cause slow loss of coolant but should be corrected.
Buy a new gasket and scrape the old housing and mount surface clean with a putty knife. You can use a gasket sealer, most just assemble dry with the new gasket. Torque evenly and not much over snug. Leak-be-Fixed.
You're missing something very important.
To correct any problem you must establish a factory suggested setting which establishes a baseline.
The OP has done some adjustments prior to locating the vacuum leak via a smoke test.
No "crazy river" trip as you are indicating just returning to a logical progression to resolve
I can't stand to see Ps2cho go nutty chasing ignition ghosts when other shops basically eliminated ignition months ago. As far as working toward a factory baseline verifying fuel and timing, that is a good thing for engine health and performance. However, none of that effort will solve for this ambiguous idle miss.
The concern is what this tech said as being construed for direction. I maintain he offered questionable advise.
1) 1.266 k Ohms
2) 1.271 k Ohms
3) 1.248 k Ohms
4) 1.263 k Ohms
5) 1.227 k Ohms
6) 1.107 k Ohms
They look pretty linear except Plugs 3 and 4....Are they within spec or could they be suspect? These plugs are about 6 months old since I bought them new. OEM Bosch ones.
I pulled out my ignition tester that I have....No idea how to use it, maybe someone here knows? It has a timing gun on the side. Here's a pic of it:

Found it on ebay for $20

Are there any DIY articles on adjusting the timing yourself on w124's? I have all the tools needed. I'd rather do it myself than take it to the shop and have someone pay to do it. Once I have the timing checked and checked off the list....then the fun begins as there isn't a whole lot left...
Last edited by ps2cho; Jul 21, 2008 at 09:22 PM.
I pulled out my ignition tester that I have....No idea how to use it, maybe someone here knows? It has a timing gun on the side. Here's a pic of it:

Found it on ebay for $20

Are there any DIY articles on adjusting the timing yourself on w124's? I have all the tools needed. I'd rather do it myself than take it to the shop and have someone pay to do it. Once I have the timing checked and checked off the list....then the fun begins as there isn't a whole lot left...
Any progress on your issues. I was actually talking with my Dad a bit and he was wondering if you my might have some valve issues in the head. have you ever had the head or valves redone? You have about eliminated all the periferal possibilities I wonder if it is just a mechanical issue.
Any progress on your issues. I was actually talking with my Dad a bit and he was wondering if you my might have some valve issues in the head. have you ever had the head or valves redone? You have about eliminated all the periferal possibilities I wonder if it is just a mechanical issue.
No the head/valves have not been touched to my knowledge...I should probably have the valve checked for the correct torque (right?).
I just bought an oxygen sensor tester today and this tester will allow me to see the oscillations and determine if this is a rich/lean misfire with certainty. Depending on what it tells me....it can take me different directions.
Soon as we are settled down in the new house I gotta get cracking on it again.


