bud1326

I am at my end of my rope. My 2002 S 430 with 130k, has a problem since I bought it July, and no one can find the problem. When I am driving around town, 30-35 MPH, stopping at lights and stop signs, when I start to move out, it will hesitate for a second or longer and then it takes hold and moves out. Often it will do this as I am increasing speed until it gets up to about 35 MPH. The car does this regardless of outside temp, or engine temp, which never gets above normal.
The servicer I use has a couple of factory trained techs and is the only servicer in this town that services MB. The gas pedal was replaced, no change, the MAF was replaced, no change. The throttle body was cleaned along with the injectors, with Seafoam or something like that, no change. To make matters worse, the techs find no fault codes, and they can't get it to act up when they test drive it. I asked them to replace the conductor plate and data plug and see it that helps. They took the plate out and could find nothing wrong, and the O rings on the plug assy were OK, no leakage. Why they can never get the car to malfunction when they drive it is a mystery. I just don't know what to do next. I can't sell it in this condition except for parts, I can't take a trip in it in this condition, so I just hate to give up. I soon will exceed the price I paid for it.
Does anyone have a suggestion that might help? Anything?

Jack_88

When it is hesitates, is it revving but not moving or is it not moving because it's not revving? Check your transmission control unit for signs of oil, especially around it's connectors. It's the small black box with two plugs in with the underhood fuses. Oil can wick it's way up the wire if the electrical connector fails at the transmission, a very common issue. That can result in odd, intermittent faults that don't always produce a code. Also make sure your cowl drain is not clogged. Just a thought, at least it's quick and free to check.

bud1326

You can see the tach drop off to almost idle when it does hesitate and often let off the gas a bit and push down will get it going again. Often tho, it will go a few feet and drop out again for a secs and then be ok, and above 2k rpm, it performs just fine. Today, I brought it in to the shop, I had bought a new conductor plate and connector plug and asked them to replace it with the new ones. They opened the transmission and checked the plate and the plug and everything was ok. No oil on the plug and no oil in the black box. No reason to replace the new parts. They drove it after that and found nothing wrong with it. I drove it and it did the same thing it always did, same hesitation problem. They also replaced the fuel filter.
The cowl drain was clean and no sign of water stains on the light tan floor mats on pass side front or back.

DrDoe

Strangely but I had hesitation issues shortly after I replaced all filters including the fuel filter on my 04 S430. The issue come when I came into a stop. It happened sometimes and not all the time. It seems the engine wanted to die. There was no engine rev when I hit the gas and it took a few seconds for the car to move.
My 04 S430 engine had a leak from the upper valve gaskets so I changed all 3 breather hoses when I performed that surgery. While at it, I also used MAF cleaner for the sensor and I wiped clean the dirts from the throttle valve.
The hesitation issue went away afterward. The breather hoses are cheap and I would suggest you give that a try.
Perhaps a trip to the dealer for proper diagnostics? Good luck!

_Ryan

You need to find another place that can service your car. Your issue should be fairly easy to diagnose. Unfortunately, it's very hard to diagnose without doing some testing. I would check fuel pressure, probably while driving and see if it drops as it hesitates. Check for misfiring, check for vacuum leaks, check a lot of things that can cause that issue. You can shotgun parts at it all day long, but as you are finding out, doing it that was rapidly depletes the bank account with no improvement. A proper diagnostic is what you need.

ibeforreal

+1 on the fuel filter.

bud1326

I will follow your suggestion and replace the hoses and see what it does. It's a 2002 so the hoses may be leaking some and should be replaced anyway.
Thanks for the help.

DrDoe

Here is the list of items I bought for the 04 S430. I didn't see any cracks on the hoses but they seem to be restricted from the oil wastes.

1120180209
Crankcase Breather Connector; Crankcase Ventilation Hose Connector $2.92 2004 S430 1x
1179901578
Crankcase Breather Hose Connector $2.11 2004 S430 3x
1120180482OE
Crankcase Breather Hose; For Full Load Crankcase Ventilation; at Valve Cover $13.44 2004 S430 1x
1120180282OE
Crankcase Breather Hose; For Partial Load Crankcase Ventilation, Center Portion $8.16 2004 S430 1x
1120180182OE
Crankcase Breather Hose; For Partial Load Crankcase Ventilation, Lower Portion $12.96 2004 S430 1x
1120180382OE
Crankcase Breather Hose; For Partial Load Crankcase Ventilation, Upper Portion $12.48 2004 S430 1x

Astro14

A clean MAF and clean throttle body would be my first place to start. They get dirty and can cause exactly what you describe. Be certain that you use only MAF cleaner on the MAF...nothing else...

DrDoe

He mentioned in his posts that he replaced the fuel filter and MAF already.
He also cleaned the throttle valve with Seafoam. What else is there?
I assumed the parts are new and OEM. I didn't clean mine with Seafoam but I assumed that product is ok.

Jack_88

I like the hose suggestion, but it could also be a sensor going out.

bud1326

Thanks for the list. I am going to order them now and even if it does not cure the problem, it won't hurt and it's time they should be replaced anyway, before they do cause problems.

Astro14

Seafoam has its fans...but I am not among that number...I would guess that we can assume the throttle body is clean. Beyond clean, however is proper response. I am not near my XENTRY machine...but on Volvos, you could use the software to do a sweep of throttle position and see if the throttle position sensor, built into the body itself, was providing good data back to the ECU...and that test: throttle body response would be interesting.

I've been through a few MAFs on my Volvos - and found that the aftermarket ones are usually junk, unless it's a Bosch, who makes the OEM MAF...

bud1326

The new MAF is a Bosch. I made sure the new one was after reading so many postings on this forum about the short life copies. The original was a Bosch and must have been in since it was new, 130k ago.
So, you have a 1932 Packard, Classy car. I used to see all of those running around when I was a kid. Rich people drove them and Cadillacs. My buddy had a 1918 Studebaker we were driving around in a few weeks ago. Sure gets the looks. All original, but needs overall cleaning and new paint.