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C43 low on power, poor cold start, off-idle hessitation
Hi all, Got some issues with my 99 C43 / 5.4ltr. First off, cold start is not real good, seems like its lean on fuel at start up, but only for the first start. If you shut it straight off then start again, its fine. Secondly, it seems to have a bit of an off-idle hessitation that makes it difficult to drive smoothly at low speeds. Third, there is a rattle at idle that goes away as soon as you touch the throttle, appears to be coming from timing chain, but cant seem to narrow the sound down to one side or the other. Does this with belt on or off. Forth, it seems to be losing low down torque, up higher in the revs it seems reasonably good, not what it should be, but floor it off the line from a standing start id expect easy wheel spin, 18 months ago it would spin off the line at about 1/2-3/4 throttle. If the traction control cuts power at low rpm for wheel spin, the power comes on very strong and seems a lot better than if it is a straight up punch the throttle with no traction control intervention, not sure why this is. I have replaced the following items over the past 18 months: - Timing tensioner - plugs 40,000klms ago - plug leads ( factory OEM kit ) - coolant temp sensor - cam sensor - crank sensor - MAF ( 3 weeks ago, genuine OEM ) - intake manifold gaskets - variable runner vacuum hose - throttle body gasket - rubber hoses between intake and rocker covers - pedal position sensor - rocker cover gaskets - water pump - fan clutch - idler pulley - tensioner pulley - MAF intake elbow rubber seals - fuel pump - fuel filter - radiator - ESL - O2 sensors ( genuine Bosch ) - Lateral accelorometer ( silver one in the boot ) - transmission electrical connector There may be a couple other items i have replaced that ive forgotten. I have not replaced coils or knock sensors, but coils have been removed and put back in different spots before with no change. what could cause this thing to seem down on power the way it is? Could cam timing be out due to worn parts? |
I'm not sure about the timing being worn down causing that. My original 4.3 motor had 297k miles on it. The last 100k miles I barely maintained it and abused it relentlessly because I was just going to put a 5.4 in it so I had no reason to continue taking good care of it. I expected to kill that motor doing oil every 15k miles, full throttle launches and burnouts all the time. The timing chain had already started making a rattle at idle at around 230k miles, so it was kind of an experiment to see how much abuse the motor could take with all those miles.
I only did basic stuff to keep it running and abused it the entire time. At 297k miles it was still just as powerful. Was still getting to 60 a bit faster than the factory spec of 5.9sec. I went ahead and put a 5.4 in it anyway. With all the wear my chain had, it didn't lose any power. I doubt your's has. |
Are there any codes? Do you have a wideband on the car? I don't think it's timing related unless you had the chain off recently to install cams or something. Those chains are pretty strong and I've never seen them skip a tooth
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Intake manifold gaskets were replaced??
did you separate open the intake manifold? I bet you have a vacuum leak somewhere |
No codes any time ive had it in to the workshop, but this being a Euro spec car there is no check engine light either. ive not had the chain off at any point, i doubt its even been off. |
Originally Posted by PJmak
(Post 7376785)
Intake manifold gaskets were replaced??
did you separate open the intake manifold? I bet you have a vacuum leak somewhere |
I dont know about the rattle or if thats related to the issue but even tho your maf is good, check it and make sure its not contaminated
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Originally Posted by PJmak
(Post 7376945)
I dont know about the rattle or if thats related to the issue but even tho your maf is good, check it and make sure its not contaminated
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When I replaced my maf, my car felt like it gained 40hp
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Originally Posted by PJmak
(Post 7376996)
When I replaced my maf, my car felt like it gained 40hp
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rattle is usually exhaust related. def check the codes even if there werent any codes last time. those vacuum leaks can be tough to find sometimes but spray around and see if you can find a crack or something
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Originally Posted by mickey13
(Post 7377232)
rattle is usually exhaust related. def check the codes even if there werent any codes last time. those vacuum leaks can be tough to find sometimes but spray around and see if you can find a crack or something
The rattle sure seems to be coming from up the front more so than anywhere near the exhaust, but ill check that out. All i read seems to suggest the chain guides are pretty much a life time part and dont really cause issues, the chains seem to be mixed opinions, there are lots saying that the chains are no issue, and just as many saying theyve found them stretched to buggery. If the chain was stretched and cam timing was out, would this in turn directly affect spark timing? Is spark timing triggered by cam sensor or crank sensor? |
Would this rattling noise be causing timing retardation due to knock sensors picking it up? If not the cam chain what else would cause this rattle that goes away with a 100-200 rpm increase? |
this is timing chain rattle.
the video implies it's the harmonic balancer, but it was not. it was the chain (this is my car) |
How much influence does the transmission control unit have over off idle hessitation and surging at low RPM slow take off? |
Originally Posted by Sulaco
(Post 7378145)
this is timing chain rattle.
https://www.youtube.com/watch?v=HvWwCEyWSx0 the video implies it's the harmonic balancer, but it was not. it was the chain (this is my car) |
Who replaced all of those components? When did you first notice this issue? I would think there is a higher likelihood of something not being installed correctly (versus a part you haven't changed failing) and it'd be easier to diagnose if we knew when this began relative to what components had been installed around that time. I would have gone with PJ with this being a MAF issue but there are a lot of variables going on here and you mentioned replacing the MAF recently. Honestly, if we can't figure it out pretty quickly, it'd probably be worth the money to pay the dealer or an independent for a diagnosis.
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Originally Posted by ECTurboGSX
(Post 7379143)
Who replaced all of those components? When did you first notice this issue? I would think there is a higher likelihood of something not being installed correctly (versus a part you haven't changed failing) and it'd be easier to diagnose if we knew when this began relative to what components had been installed around that time. I would have gone with PJ with this being a MAF issue but there are a lot of variables going on here and you mentioned replacing the MAF recently. Honestly, if we can't figure it out pretty quickly, it'd probably be worth the money to pay the dealer or an independent for a diagnosis.
The issue started coming up before i had the intake manifold gaskets replaced by a workshop with brand new genuine Merc parts. When they did this, they pulled the vac hose out for the variable intake flaps and replaced it with one that was too small to fill the hole, against my advice. They sealed around that with silicone, which made the car run perfectly smooth for about a week. They then took the manifold back off and replaced the hose with a much fatter one, and sealed around that, although apprently the hose is a snug fit. The issue has been there since just after this. |
Originally Posted by W202AMG
(Post 7379169)
I replaced the majority of them, and theyve all been checked a few times, theyre done right. I did 11 years working on Corvettes and made quite a few of those run smoothly. The issue started coming up before i had the intake manifold gaskets replaced by a workshop with brand new genuine Merc parts. When they did this, they pulled the vac hose out for the variable intake flaps and replaced it with one that was too small to fill the hole, against my advice. They sealed around that with silicone, which made the car run perfectly smooth for about a week. They then took the manifold back off and replaced the hose with a much fatter one, and sealed around that, although apprently the hose is a snug fit. The issue has been there since just after this. |
The gaskets were reused, they had only been in 4 weeks. |
Originally Posted by ECTurboGSX
(Post 7379178)
The intake manifold had to come back apart to replace with the fatter hose, correct? Did they replace the seal that time? This thread seems to have a lot of information about this particular topic: http://www.benzworld.org/forums/w163...questions.html
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Did you try to diagnose the car while driving it..?,,
it may helps to narrow the issues, last month, i did swap for my friend, we forced losing power at high idle, diagnose the car so many times, no codes founded..!,, after that, we decided to diagnose the car while driving, after around "10" minutes, ECU deducts wrong signal back from knock sensor bank [2/R]..?!?!,, replaced the two knock sensors, bingoooooooo, everything comes sooo great..:) -;ZAYED;- |
Originally Posted by cm60k
(Post 7379302)
Did you try to diagnose the car while driving it..?,,
it may helps to narrow the issues, last month, i did swap for my friend, we forced losing power at high idle, diagnose the car so many times, no codes founded..!,, after that, we decided to diagnose the car while driving, after around "10" minutes, ECU deducts wrong signal back from knock sensor bank [2/R]..?!?!,, replaced the two knock sensors, bingoooooooo, everything comes sooo great..:) -;ZAYED;- Did the knock sensor code go away after turning off the engine? what is the part number for the knock sensors? |
We drove the car without hood, for a while..:D,,
i think, there's a "Bluetooth" port conversion, but not that sure about it..!,, there wasn't code for knock sensor, but after driving, ECU catch the fault back signal from know sensor, and suddenly, code appears then vanished, it was "P1386"..!?!?,, we stopped the car, diagnose the car again, no codes,, after that, replaced the knock sensors, NO issues then..:) i used knock sensors from "M156" Engine;- *OEM # "004 153 90 28" *Bosch # "0 261 231 188" -;ZAYED;- |
Originally Posted by cm60k
(Post 7379333)
We drove the car without hood, for a while..:D,,
i think, there's a "Bluetooth" port conversion, but not that sure about it..!,, there wasn't code for knock sensor, but after driving, ECU catch the fault back signal from know sensor, and suddenly, code appears then vanished, it was "P1386"..!?!?,, we stopped the car, diagnose the car again, no codes,, after that, replaced the knock sensors, NO issues then..:) i used knock sensors from "M156" Engine;- *OEM # "004 153 90 28" *Bosch # "0 261 231 188" -;ZAYED;- What was your reason for using the M156 knock sensors? Does anyone have any info on any sort of diagnostic equipment i can buy for a Euro spec car that will allow me to check most modules? Are there any around that i can make changes to the settings within the ECM? |
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