Two Second Acceleration Lag – Fuel or Air Flow Problem? (260E)
 

Car: 1989 260E, 198,000 miles.

There is a one to two second lag in acceleration when I floor the accelerator (but without engaging the kick-down switch) whether from standstill or at speed.

The pedal will contact the floor, and the fuel economy needle will move, but the tachometer will not budge for a second or two. Then it surges, making for a jerky ride. I was initially told this was a fuel delivery problem, but I am wondering if it could be an air flow issue.

I know I am running lean. The last thing I did to the car was replace the Thrust Cutoff/Throttle/Decel micro switch to correct a fast idle.

Help. I want smooth, steady acceleration.

I had that problem withy my s500 but it was bad gasoline.

My 1989 260e used to do the exact same thing... unfortuanly I never realy did figure out what the deal was with it but it did often have an O2 sensor fault set by the ECU (even though I replaced it).

I guess this post is not much help beyond... "Hey.. I've had this problem too with a 260E". It never really got worse though.... I just had to think twice about jumping out into any traffic.... :(

It only occurs on rapid acceleration -- when I immediately floor the accelerator. If I depress the accelerator gradually, there is a smooth power curve and no lag.

I compare it to turbo lag since it appears the car is waiting for something to "spin up" before it accelerates.

well in that case let me say it ! My 260E does the same !!
but then again i think that's just lack of power because i've never seen a 300E with a 3.0 or 3.2 do that.
just underpowered i'd say..

I have 300E 3.0L but I also have acceleration lag. It eventually starts accelerating good after like 3 seconds when it reaches 3000rpm. I dont think its normal and from what ive read on this forum it must be vacuum leak. I might be wrong. Im thinking to look for leak around Idle air valve hoses but it requires to remove a lot of things off the engine. Im NYC its kinda cold out to do it. Once itll be warm Ill change hoses and couplers. It seems to change RPM when I spray carb cleaner around hoses so I assume vacuum leak sucks carb cleaner in intake manifold and increasing RPM. Like I said I might be wrong. I had 420sel before. It had same problem (acceleration lag) but I never went changing any hoses because the car wasnt in good shape to invest into. I hope my thoughts help in some way. Good luck.

If all else fails... just slap a Turbo badge on the passenger side of the trunk. :D

Marty ...I was thinking of putting twin turbo badge off 300zx i think itll work even better. 1 turbo badge=good. 2=better. Buy the way dont tell me that your benz is has the same lag. Im very aggravated about accel lag :mad:
let me know

It's interesting what you say about vacuum leaks. That’s on my list of things to get to (total hose replacement).
I developed a bad stalling problem about 6 months ago that I traced to a crack in the bottom of the valve cover side of the breather hose that goes to the top of the air cleaner housing... taped it till I could get a replacement.
But I was never able to track down any other leaks with propane so I keep putting it off.

I’ve actually got her running better now than she has been in a while and have just a few more issues to address before I can go after non-essential repairs.

That said I think there is a little lag inherent in the M103... 3000+rpm's is where she really seems to come into her own...

Vacuum leaks and general tune up items needing attention would certainly accentuate that though...

Keep fixin em...

Searching the old threads and came up with this one, but there's no solution to the problem. My car has a significant lag when I depress the accelerator before the power really kicks in. Has anyone had a similar experience they have been able to resolve?

Thanks, Dave

The car I had that problem with (260E) has gone to the "Great Autobahn in the Sky." Never found out what it was, but the tech at that time was assuming the fuel accumulator.