Wrong fuel injectors? - PeachParts Mercedes-Benz Forum

embe560sl · #1 06-02-2007, 01:46 PM

I asked this question on the Sl forum with only one response but would really appreciate more opinions.
My 89' 560SL is presently running a very rich mixture. I am trying to discover the cause. One 'Techie' input has been that my fuel injectors are the OEM 'iron type' and should be changed over to the modern brass ones. This sounds rather odd to me but obtaining the correct answer will establish whether this 'techie' is full of it and to be avoided

An thoughts on what might be the cause of this rich mixture would be greatly appreciated.

Carson357 · #2 06-02-2007, 04:08 PM

there are manythings that can cause a rich mixture, and injectors are a possibility, but you would likely be better off paying for a proper diagnosis rather than taking the shot gun approach, first ting i would check would be if it has fuel control, the ov relay can be defective causing no power to be sent to the engine control module, also the fuel distributor piston or the cold start injector could be leaking allowing extra fuel to be introduced, best case scenario, you can get it to lean by adjusting the mixture at the enrichment tower.

embe560sl · #3 06-03-2007, 01:19 PM

Quote:

Originally Posted by Carson357

there are manythings that can cause a rich mixture, and injectors are a possibility, but you would likely be better off paying for a proper diagnosis rather than taking the shot gun approach, first ting i would check would be if it has fuel control, the ov relay can be defective causing no power to be sent to the engine control module, also the fuel distributor piston or the cold start injector could be leaking allowing extra fuel to be introduced, best case scenario, you can get it to lean by adjusting the mixture at the enrichment tower.

'many things' is the most frustrating part of this problem. If I'm not careful, I can see I could be subject to paying many shop hours with unnecessary replacement parts if I cannot find the right people. I will certainly pursue a proper diagnosis.....if there is such a thing. I am curious as to the lean adjustment you say can be made at the 'enrichment tower'....what/where is this located

jhodg5ck · #4 06-03-2007, 02:39 PM

what are the symptoms you are experiencing? I would think by 89 you would have the later/updated style of injector.

There are two ways to adjust the mixture, one is the tower in front of the fuel distributor which effects mixture up to 2500 rpm. The other is the EHA, the black box strapped to the side of the FD.

You can read up here on adjusting the CO:
http://landiss.com/mixture.htm

Jonathan

Carson357 · #5 06-03-2007, 03:06 PM

that is just it, a competent shop will determine cause before they throw parts at it. should be a fairly straight forward diagnosis, i am sure i could do it quickly, just difficult without actually seeing the car, the adjustment is under the air filter area, but they just don't go out of adjustment, something has definately caused the issue. it may have a tamper plug in the end, but the adjuster is 4mm, turning clockwise enrichens, counter clockwise leans. be sure to remember how much you turn it so you can go back if you need, do not go beyond 1/4 of a turn, do it in very small increments. you can check it using a meter.link in post above and the one below may help.

http://www.peachparts.com/shopforum/showthread.php?t=145244&highlight=lambda

Quote:

Originally Posted by embe560sl

'many things' is the most frustrating part of this problem. If I'm not careful, I can see I could be subject to paying many shop hours with unnecessary replacement parts if I cannot find the right people. I will certainly pursue a proper diagnosis.....if there is such a thing. I am curious as to the lean adjustment you say can be made at the 'enrichment tower'....what/where is this located

embe560sl · #6 06-04-2007, 02:57 PM

Thanks jhodg5ch and Carson357.........your input is very enlightening and most welcome.
I am absorbing all the information put forward

hoping that I will be able to sort this problem out myself, as my confidence in local technicians

is non existent. I am delighted that this forum has such helpful knowledgeable folk. Thank you all and every.

just-n-time · #7 06-07-2007, 09:41 PM

I am sure you know this ,But just in-case,the o2 sensor may be the cause also.It tells the EHA to lean or richen as required.Some one check me on this but I think thats wright.

david s poole · #8 06-08-2007, 10:22 AM

you are correct.

embe560sl · #9 06-09-2007, 12:39 PM

Quote:

Originally Posted by just-n-time

I am sure you know this ,But just in-case,the o2 sensor may be the cause also.It tells the EHA to lean or richen as required.Some one check me on this but I think thats wright.

I see (said the blind man) I will look into this...is there a test that can be run to determine whether it is at fault?