1988 300TE - Misfires - Where to go now?
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It will cost me $70 to get a new Bosch rotor+cap from a local store
Do you think I should do it?
I think there's only a few things left that I can replace before routing this misfire down.
*Rotor+Cap
*ECU
*FPR
*EHA (I have another one that I will test tonight!)
I believe those are the only things left that I have not replaced yet that would cause a misfire.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Without reading through all 3 pages of this post, have you tried taking to an indy to have him diagnose it? I wouldn't think he would charge much. I would think if the cap and rotor look good that there is little chance of a problem. How do the plugs look? Did you replace any injectors yet? Sorry for not reading the whole thing; I'm lazy. 
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Without reading through all 3 pages of this post, have you tried taking to an indy to have him diagnose it? I wouldn't think he would charge much. I would think if the cap and rotor look good that there is little chance of a problem. How do the plugs look? Did you replace any injectors yet? Sorry for not reading the whole thing; I'm lazy.
Yes I have taken it to 2 separate mechanics. Injectors and seals were done by previous owners (in the attempt to fix the problem too!) and we have the receipt. Plugs are perfect since we did the Valve Stem Seals and not a drop of oil used.
I just spoke to my dad and he said we replaced the coil with a used one (but didn't feel any different) so the coil isn't the problem.
I am planning to keep the car until it gives up, so I believe it would be a good deal to just go ahead and get the rotor+cap for $70 locally (brand new Bosch ones) and if it doesn't fix it - just throw it away in a box for when the car will need it replaced in the future.
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I have made sure there are no vacuum leaks (including brake booster lines etc) myself, and 2 Indy's have also tested it too, so vaccum leaks are off the list.
Now, regarding the O2 Sensor, I have disconnected it from outputting to the ECU, but the misfires continue as normal. So for right now, the O2 isn't causing the misfires correct?
As for the temperature sensor, I am looking online at part stores for the price of one and "temperature sensor" isn't showing. Does it have a different name? I am trying to see if there is a relationship with anything due to the fact the car does not misfire for about 10 seconds from a real cold start. So obviously, something after 10 seconds kicks in and causes the misfire.
Also I will put 10/50 back in next time I get my oil changed as I'm not using a drop of oil now.
Lastly,
3. Check fuel pressure and volume at fuel distributor.
----
Aside from the misfire, today my battery is no longer charging
All warning lights are lit up in the dash (including empty tank, ABS, etc) and the car died on me. Just another thing to add to my problems. We replaced the alternator bushings when we got the car along with the voltage regulator and OVP. hmmm...looks like this has gotta be fixed first now.
Last edited by ps2cho; Jan 3, 2008 at 12:38 AM.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
During the first 10 seconds the RPM would drop slowly I think. Is is falling to a certain RPM where the misfire begins, and if so, can you immediately rev it up past that point and get it to run smoothly again? It is starting to sound like the ECM. That would be looking at the distibutor pick-up sensor (I'm assuming a lot here; I don't know if these use a typical ignition system from the '80s or not) and processing that info to control the primary signal to the coil. If the pick-up sensor in the distributor is flaky or the ECM is going bad, it could cause your problem. Have you tried a new distributor from a junk yard or E-Bay?
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During the first 10 seconds the RPM would drop slowly I think. Is is falling to a certain RPM where the misfire begins, and if so, can you immediately rev it up past that point and get it to run smoothly again? It is starting to sound like the ECM. That would be looking at the distibutor pick-up sensor (I'm assuming a lot here; I don't know if these use a typical ignition system from the '80s or not) and processing that info to control the primary signal to the coil. If the pick-up sensor in the distributor is flaky or the ECM is going bad, it could cause your problem. Have you tried a new distributor from a junk yard or E-Bay?
Yes i just replaced the disty with another used one and problem wasn't affected. I really hope its not the ECU because thats darn expensive.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Yes it starts and revs up to ~1000rpm, but the misfire is not present because after it calms down to ~700rpm and starts misfiring, I can rev it back up to 1000 and still feel it misfiring.
Yes i just replaced the disty with another used one and problem wasn't affected. I really hope its not the ECU because thats darn expensive.
Yes i just replaced the disty with another used one and problem wasn't affected. I really hope its not the ECU because thats darn expensive.
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Are the ECU's the same on all w124's or do the TE's differ? Or what years match? I know off the top of my head the 87' ECU differs from the 88, but what years do they go up to that would work? 88' - xx'?
Last edited by ps2cho; Jan 4, 2008 at 01:52 AM.
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Ok to update: My alternator died a few days ago. All warning lights were on the day prior and I was a little confused...then the next day it wouldn't start up(aka battery dead). Got a new battery via warranty(thank god costco was right across the street) and got her home. Voltage was reading 12.4v idling and if I turned on the lights she would die.
Just got my new alternator plugged in and the car's alive again! Problem solved. I am getting a solid 14.4v idling.
At the same time I put in my new rotor+cap and the misfire is still present. I wasn't expecting it to fix anything, but they were pretty cheap and its an important thing to rule off.
:angry: where will this end?
Alright seriously, Now that I have replaced the plugs, leads, cap, rotor and coil...Isn't that the entire ignition system except the ECU? Can we rule this out now and concentrate on the fuel delivery or is there something I am missing.
The next culprit would be the fuel pressure regulator for sure. I gotta figure out how to test the fuel pressure before I head off and spend more money (its about $50 used)
Just got my new alternator plugged in and the car's alive again! Problem solved. I am getting a solid 14.4v idling.
At the same time I put in my new rotor+cap and the misfire is still present. I wasn't expecting it to fix anything, but they were pretty cheap and its an important thing to rule off.
:angry: where will this end?
Alright seriously, Now that I have replaced the plugs, leads, cap, rotor and coil...Isn't that the entire ignition system except the ECU? Can we rule this out now and concentrate on the fuel delivery or is there something I am missing.
The next culprit would be the fuel pressure regulator for sure. I gotta figure out how to test the fuel pressure before I head off and spend more money (its about $50 used)
Last edited by ps2cho; Jan 7, 2008 at 11:30 PM.
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From: OC
97 E420, e320 Wagon, e38
check your spark plug connector boot, and inspect your spark plug wire connector at the cap!
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I have my FPR on its way gentlemen.
By time I have this fixed, the fuel injection and ignition will be brand new
Let's pray the FPR ends this prolonged problem. Still have not spent $500 on parts towards fixing this yet
I'm doing pretty good.
Last edited by ps2cho; Jan 13, 2008 at 03:31 AM.
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FPR? Is that a Fuel Pump Relay you're referring to? If so, as a test I believe you could have just temporarily jumped it to see if the problem goes away. The jumper has to go between terminals 30 and 87, which will make the pumps run continuosly.
I've got a special made u-shaped #16 wire in my glove compartment in case the "relay" ever fails on me while on the road. BTW, its much more then a simple relay, in there is a micro controller chip and a bunch of additional electronics. Very advanced for an 86 car (in my case) anyway. In comparison most American cars of the time barely had any electronics (besides the radio) at all.
I've got a special made u-shaped #16 wire in my glove compartment in case the "relay" ever fails on me while on the road. BTW, its much more then a simple relay, in there is a micro controller chip and a bunch of additional electronics. Very advanced for an 86 car (in my case) anyway. In comparison most American cars of the time barely had any electronics (besides the radio) at all.
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FPR? Is that a Fuel Pump Relay you're referring to? If so, as a test I believe you could have just temporarily jumped it to see if the problem goes away. The jumper has to go between terminals 30 and 87, which will make the pumps run continuosly.
I've got a special made u-shaped #16 wire in my glove compartment in case the "relay" ever fails on me while on the road. BTW, its much more then a simple relay, in there is a micro controller chip and a bunch of additional electronics. Very advanced for an 86 car (in my case) anyway. In comparison most American cars of the time barely had any electronics (besides the radio) at all.
I've got a special made u-shaped #16 wire in my glove compartment in case the "relay" ever fails on me while on the road. BTW, its much more then a simple relay, in there is a micro controller chip and a bunch of additional electronics. Very advanced for an 86 car (in my case) anyway. In comparison most American cars of the time barely had any electronics (besides the radio) at all.
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You could have a service shop test the fuel pressure in the system and rule out the regulator. But if the FPR is already on the way...
Also, it would be good to check for how long the minimum system pressure is retained, so as to check the fuel accumulator.
Also, it would be good to check for how long the minimum system pressure is retained, so as to check the fuel accumulator.
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The thing about getting the fuel pressure checked at a shop is that the cost of getting them to check costs me than can bag me a new one....so why not just get a new one?
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Well I got the package today, but it seems they messed up and sent me a fuel pressure damper (it said regulator on the auction)....
The thing about getting the fuel pressure checked at a shop is that the cost of getting them to check costs me than can bag me a new one....so why not just get a new one?
The thing about getting the fuel pressure checked at a shop is that the cost of getting them to check costs me than can bag me a new one....so why not just get a new one?
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I heard from somebody else that there 290E IIRC had this problem (not near the extent mine is at) and the FPR fixed it. I just hope it will do the same for me.
I mean what else could there be left except the ECU?
What about the EZL? Could that cause the misfire because I've seen them for like $30 and thats a simple plug-in and go.
One day I'll get this fixed....
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Its gotta be something simple due to the fact it doesn't affect anything apart from the shaking misfire....No problems to redline, no weird anything.
I heard from somebody else that there 290E IIRC had this problem (not near the extent mine is at) and the FPR fixed it. I just hope it will do the same for me.
I mean what else could there be left except the ECU?
What about the EZL? Could that cause the misfire because I've seen them for like $30 and thats a simple plug-in and go.
One day I'll get this fixed....
I heard from somebody else that there 290E IIRC had this problem (not near the extent mine is at) and the FPR fixed it. I just hope it will do the same for me.
I mean what else could there be left except the ECU?
What about the EZL? Could that cause the misfire because I've seen them for like $30 and thats a simple plug-in and go.
One day I'll get this fixed....
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For $30 I'd replace it yesterday. I apologize because you probably said this somewhere a while back, but does it accelerate properly? Is the shaking and misfire only at idle? I was thinking you said something about poor gas mileage, too. Did you ever run a compression test? I was thinking you did. Sorry if this has been hashed our already.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Yes acceleration has no problems all the way to the redline in all gears. Its misfiring all the time, but can only be felt at idle when the car is not moving. Compression is ~185 on all cylinders. I do get poor gas mileage (~14 city 19 freeway), although I am not sure what a 300TE "should" get.
Off subject- My company is giving me a Dodge Caliber.
I sure as heck don't need 2 of them. I may be closer to getting a real car like yours. 
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Maybe the HV is leaking away somehow, have you tried looking at the running engine at night with no light? Look for any sparks around any HV ignition system parts, that should be a clue to the HV leak. Also, rev up the engine and make sure there are no random sparks to be seen anywhere.
Alex
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This HAS to be an electrical problem, one cylinder is definitively missing. Sounds like it could be one of the plugs, cable or cable boot, or distributor, rotor. I know you've already changed all those, but it really still points in that direction. I don't think it has to do at all with fuel pressure, so unfortunately doubt that changing the fuel pressure regulator unit will help.
Maybe the HV is leaking away somehow, have you tried looking at the running engine at night with no light? Look for any sparks around any HV ignition system parts, that should be a clue to the HV leak. Also, rev up the engine and make sure there are no random sparks to be seen anywhere.
Alex
Maybe the HV is leaking away somehow, have you tried looking at the running engine at night with no light? Look for any sparks around any HV ignition system parts, that should be a clue to the HV leak. Also, rev up the engine and make sure there are no random sparks to be seen anywhere.
Alex
The cable boot is part of the plug correct? We replaced the plugs with new ones.
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From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
Did you pull the plugs and see which one looks different? Also, if you idle it for 15 minutes and shut it off, one plug should feel a lot cooler than the rest.
