Help! Am running out of things to try....

[Max J. Sandler]

My 87 560 SL has had fuel injection problems from the day I bought it. First I wouldn't go through NJ inspection. $ 600+ later (and this wasn't a dealer), they put in a new EHA valve that appeared to solve the problem, but the car ran poorly. After making it a little richer with the mixture adjustment, it ran well, idled well, but got 10-12 MPG no matter how I drove. I found a good used fuel distributor which seemed to help throttle response, but the mileage is still poor. Plugs foul now and again. Car starts hard hot or cold. Mixture adjustment seems to have little effect. What's galling is that this car only has 106,00 miles on it. My 86 560 SEC has over 150,000 miles, literally starts in half a turn hot or cold, runs great, and gets 15-17 MPG.

As loathe as I am to randomly throw parts (and money) at the car, I am tired of playing with it, and just want to drive and enjoy it. Am I doomed to going to the dealer, hat and checkbook in hand? The independent mechanics around here don't seem to have the diagnostic equipment to find the problem.

[Max J. Sandler]

Almost forgot. Have already installed all new injectors.

[ejsharp]

Well Max it seems to me that you have been messing and guessing. I'd take it to a dealer and get the car tuned properly.

[joel]

i'll second that. if all else fail, go to the dealer.
find out what is wrong, ask for an estimate, if it seems
reasonable and within your means, go for it, if not
walk away and go to a trusted mechanic with info
about your car. good luck!

[Max J. Sandler]

Both of you are probably right, although I have a feeling that its probably not that difficult a problem, its just finding it. Unfortunately, the diagnostics on this system are pretty rudimentary, and I'm told that each component in the system has to be tested separately. If this is the case, its likely to cost $$$ at the dealer.

Oh well, the cost of owning this car is far outweighted by the pleasure it brings me.

[peterhardie]

How close are you to Little Ferry NJ? There is a great pair of techs there, call them 201-440-8864. I know a guy who drives down from MA to use them, so even if you aren't that close, it may be worth the trip. Tell them Peter sent you.

[Max J. Sandler]

Thanks, Peter. Its a bit of a hike for me, but it sounds like it may be worth it.

[jcantor]

Max,

I don't want to send you on a further wild goose chase, but did you do anything with the O2 Sensor? I had a very similar situation this spring with my '87 560SEL - poor performance, very bad MPG (~7!!) and a very obvious smell of unburned gas. After no improvement following a needed plug, wire, cap, and rotor replacement, I went after the O2 sensor and the cat.

You can hook up a meter to the O2 sensor leads under the passenger's feet. Do a search and I believe you'll find some info on the type of readings you should get. Mine was dead so I replaced it. That and some tweeking of the mixture screw by ear and I'm now getting around 20 MPG on the highway if I keep my foot out of it and ~17.5 mixed and back to normal performance.

Let us know what ends up being your solution.

jlc

[Max J. Sandler]

The O2 sensor is brand new, as is the EHA valve. My other car the 560SEC starts and runs perfectly. I'm going to park them next to each other and take electrical readings on the individual components and compare. If they check out, I'm going to swap fuel distributors. After that, and a temper tantrum, I'll take the car to the dealer.

Just guessing - but - if it hard starting hot or cold - have you checked the fuel pressure from the accumulator.?If that is good, it sounds like you might have a fuel pressure problem in the fuel distributor - if the fuel pressure is low - it can make for hard starting - as for the poor mileage and fouled plugs - could the mixture have been screwed up too rich to compensate for a lower fuel pressure? but like I said - I'm just guessing. Since you have another 560 engine it would be fairly easy to compare pressures. Worth a shot.

[Max J. Sandler]

Thanks, that's a good idea. Unfortunately, I don't have a pressure gauge and adapter for the fuel injection system. And you're right, I've had to richen the mixture to get a decent idle and throttle response, so this may be a case of the cure being worse than the disease. Thanks for doing my thinkint for me.

Max
a lot of auto parts places rent out tools - try to rent a pressure guage with adapters - will be a great week end project!

[Piotr]

Max-temper tantrums don't work - I use pouting and blaming wife ("you never give me enough time to fix _____")