Pancho

RPM or Trans prob or what ???
Vehicle seems to be stalling. At first I thought it might be a shifting prob, but sometimes it seems that it's the engine that fails to rev up. When I try to accelerate, if I give it a good dose of pedal, the engine doesn't want to rev, and then it seems at though the trans either shifts when it shouldn't, or fails to shift when it should. I can get to speed, 80 MPH+, but I have to do so with a slow steady pedal pressure.
AM guessing MAF (orig.), or fuel filter (orig.), or fuel pump (orig.), or plugs (replaced 35K ago), but really don't have a clue.
Any help determining the issue would be greatly appreciated.
Thanks

pauly24

It could be a multiple of things, but knowing the history of these cars I would definitely say MAF.
Here is how you confirm if it is the MAF. First locate the MAF sensor, there is one plug to the sensor. Disconnect this plug and cable tie it to the side so it doesn't get caught in the fan/belt when you drive it.
Take the car for a quick test spin, if its running better then its a safe bet that its your MAF.

Pancho

I've done the on/off MAF test. I'll do it again and post a follow up, but...

are we talking about the same sensor here ?
The MAF is about 4 feet from any belt,
at the rear of the intake manifolds,
at the firewall.
What sensor are you describing near the belts ?
Thanks.

pauly24

Sorry, I was talking about a clk230 komp. Either way the same principal still applies. Disconnect it and see how the car runs.

You said you have done the test, so what was the results?

Pancho

Did it some months ago for another matter.
Will do it again on the way to the office this AM
and will post follow up.

Pancho

Here's the follow up. Did the following:

1. Poured a bottle of STP octane improver into tank. Had been burning 89 octane instead of 91. Result: Helped a small bit with acceleration. Hesitation, bad lag, erratic shifting, etc. still there.

2. Unplugged MAF sensor. Did this while engine was running--engine died; at restart had CEL. Drove to work that way, and vehicle died at red light, but started up again. After parking at office garage, I connected the plug to the MAF. Result: Engine ran worse with the MAF unplugged--same bad symptoms as before, plus it died twice. With MAP plugged in again, CEL went away, but same hesitation, bad lag, erratic shifting, etc. still there.

3. Reset ECU. Result: Best improvement, but problem, though reduced a bit is still there, hesitation, bad lag, erratic shifting, etc.

I can't tell whether the lag produces the erratic shifting, or whether it's the other way around, the erratic shifting produces the lag.

I will connect it to my multiplexer this week end and look for codes and post a follow up, but instrument panel indicates no codes when I scroll through.

Question: Vehicle has the original fuel pump and filter.
1. What is the service life of the filter ?
2. How test the pump?

Thanks.

Silv430ClkR

sounds like you may hav a vacuum leak, try checking all the pcv lines for cracks and the rigid black line coming off the the firewall on the drivers side. that rigid line is a vacuum line for the gas tank. it may have come loose(happened to me). this will cause the motor to run lean and give you a rough idle and poor acceleration. also go over the whole motor with a propane canister to find the leak if it wasnt any of the lines. gaskets, fuel injector o-ringsthat hav gone bad, sticking egr valves, brake booster, the list goes on, check everything. but first check the lines. also hav you gotten any check engine lights yet? also clean the maf before buying one. i took out the sensor from the actual housing and submerged it in simple green for about 10 min. then went crazy and sprayed it down with heavy duty electronic cleaner then to make sure it was perfectly clean and dry i spayed it down with fast drying maf cleaner. worked for me(and mine was soaked in oil from the supercharger causing blowby to run through the pcv lines and drip onto the sensor) the sensors are more durable that people make then out to be(go nuts with cleaning it) let us know how you made out

also get some 93 octane in that tank and a bottle of chevron techron, and a new fuel filter. i doubt the pump went bad

Pancho

You say, "go over the whole motor with a propane canister to find the leak if it wasnt any of the lines".

What do you mean ?

Silv430ClkR

open up the valve on the canister to let the propane leak out and go over hoses,gaskets,egr valve, brake booster, fuel injector o-rings, basically any where there would be vacuum. if there is a leak the propane will enter though the leak and idle should correct itself, and then you would know thats where the leak is. do this while the car is running(at idle). my bet is on a hose or gasket. also try cleaning the maf like i said. if it comes to buying a new one, autohausaz has them for our cars for $135. same exact bosch part number. but first clean it!

Pancho

I have one of the typical MAP torch, with the disposable cylinder. I use it for sweating plumbing joints on copper tubing. Thought I had an old propane cylinder sitting around somewhere, but no. I can get a propane cylinder at Lowes, Home Depot etc. So, if I open the valve on the torch end, and glide it along the hoses, a change in the engine--a smoothing out, would indicate that I have found the leak. Your opinion--will my torch w/a propane cylinder do the job you describe ?

Another question: What is the service life of the fuel filter ? Mine is the original year 2000 filter @ 103,000 miles.

I'll try to get to this over the weekend, but have promised a friend I would bead blast a couple of Model T carbs for him to rebuild. Imagine that, 100 year old carbs. There's service life for you.

Thanks

Silv430ClkR

yeah it shoul work, just let the gas leak out(dont ignite it) and go over everything. first do a visual inspection, then try that. and clean the maf the way i described. im not too sure what the life of the fuel filter is but 100000 miles seems more than enough to make you change it anyway even if nothings wrong with it. its only a $30 part and takes literally 20min. to do, easy. let me know what happens.

Pancho

I'll clean the MAF again, hopefully this weekend. I posted this link to a How To I put together on this a couple of years ago:

http://www.panchogun.com/FVWebPhotos...-MAF-5x100.jpg

MarcusF

That's a fantastic how to. We have got to get an index of your photos!

howie

DUDE, same thing started happening to my car when I left work last night. Difference being I actually had some work done to my car at the Benz dealer where I work right before it started doing it. I had the oil changed, tranny drain plug replaced (was leaking a bit), and a tranny mount replaced. I jump in the car and it runs great at first, a little while later at a stop light the rpm drops to like 500 car starts buckling and shaking like it wants to turn off. It stayed running but upon take off it didn't want to move at all. It feels like its spooling up a turbo, lag right up through 1st gear and into 2nd, eventually clearing up at higher speeds. so weird!

I'd like to know what you figure out with this!!!

dlbehrns

autohausaz also has the MAF insert they say is made by Bosch and it sells for less than the entire unit. the sensor itself can be removed from the housing.

howie

The tech here found my problem, a Vacuum line was off. Check all your lines!