Benz260Benz

My car has been acting up pretty bad. It'll run great at times but then driving down the road the check engine light will flash on and off and I will lose power and start to slow down no matter how much gas I give it, as if I'm putting the breaks on. Then the light will go off and it'll run fine again. It is very intermittent; it'll run great all day, no problems, then the light comes on and it’s all downhill form there. if I’m going too slow or at a stoplight and the light starts to flash and come on usually the car will die, other times it just makes the RPMs jump up and down, and even sometimes just idle really low with the light on solid. I took it in to my mechanic and he found that my rain shield for the control boxes and relays in the engine compartment somehow disappeared and a large amount of water has gotten into that compartment and done some damage. I've already had to replace two relays that had water in them and my CIS-E box has some bad water damage. All that being said, my mechanic says I need a new CIS-E box but they are a bit too expensive, if anyone has an extra one or knows of a cheap one it would be really helpful. Also my mechanic isn't 100% sure it’s the box so any other ideas would help too. Your thoughts?

appatula

Honestly, look on ebay or a junkyard for the Jetronic ECU control unit (CIS-E box) There are a few on ebay right now so go write down the part number on yours and start comparing! Also I would replace the Over Voltage Protection Relay (OVP Relay)

Benz260Benz

Yeah I did replace the OVP Relay and its still doing the same thing. I looked on eBay and I only found a couple things. Is a Genuine Mercedes MSG Control Module the same as a CIS-E box? Also is a ECU ECM Computer the same as a CIS-E box? I only ask because these items are extremely cheap compared to what I thought I was going to have to pay. If these don't work I will definitely check out the junkyards around here, there are only a couple. Thanks!

YNVDIZW124

I don't think it's you CIS-E box. Replace the fuel pump relay and that should fix it.

Saijin_Naib

Do you have the m104 24v engine or the m103 engine?

YNVDIZW124

260= 2.6 m103

Benz260Benz

My mechanic put a brand new fuel pump relay in it and it still did the same thing, idled perfectly for a little bit then the check engine light started to flash and idle went haywire, then it died and the problem persisted after starting it a couple more times.

And yeah its the m103 I6

appatula

My M103 has an ECU ECM box and a ABS box. Only two boxes that were in mine so I'm pretty sure we are referring to the same thing

Benz260Benz

Wow, the price for the one on eBay is only $29.99 + shipping. The cheapest my mechanic could find used was $500 and brand new they are +$1000. Is this realistic?

YNVDIZW124

Well i can get a CIS-Box off a junk yard 260E if i can find one for you...they run maybe $20-$30??....

Well starting at the fuel pump relay....now did you check your fuel pump??

I don't think it has anything to do with the ECU because these cars can run without it just on the mechanical parts...

appatula

Yes, if he is sourcing from the dealer for a new one, absolutely. This is another reason why ebay is so useful when you own a Merc

For example:


Prices effective May 2005
Call Rusty for current pricing and to order parts:
1-800-741-5252, or email: rusty@buymbparts.com


Part Number Suggested Dealer
(no spaces) Description Retail Wholesale Cost
========================================
021545203205 ECU FOR E420 2000.00 1600.00 1200.00

Benz260Benz

I guess i don't know if the fuel pump was checked. I defintiely didn't know they could run without the ECU. If there was an electrical short in the ECU do you think it could mess with how the engine runs? It's a really weird problem. When the check engine light comes on there is usually a problem, but that problem varies. Sometimes the car will decelerate, no matter how much gas i give it and other times it will just have a loss in power (it'll still go forward just with more gas), and other times it will just stall (if i'm going slow enough). would all those be caused by a bad fuel pump?

appatula

Usually the ECU is never the culprit but in your case I'm thinking that it could very well be the problem. Swap it out, basically you need to just trial and error it especially when you can soure them off ebay or a junk yard cheap. I honestly hate CIS-E jetronic, I'm doing a complete engine management swap this summer to Megasquirt II for electronic fuel injection as well as a full Electronic Distributorless Ignition wasted spark system, no more cap and rotor.

Benz260Benz

Yeah the ECU definitely had water damage in it when my mechanic and I took it apart so I’m thinking its just shorting or something. I bought that ECU so I’m just going to put that in and see if it works, if not I have a month to send it back, which is nice. If it’s not the ECU I’m not sure where else to look, maybe crank sensor?

That megasquirt conversion sounds like a good idea. I started to put a megasquirt system on a 76' Ford 2.3L that I pulled out of a Mustang II when I was in high school. I ran out of time and never got to finish it.

ohlord

question.Have you read the codes,when the cel flashes?If it is blinking that means possible catastrophic failure and it has put you into limp mode.If the continuous injection system and ecu,the other systems are doing their job triggering the error code then the system may be fine and you need to get the code and diagnose the problem.
Before you spend a bunch on what he thinks it may be,go to a better shop that will tell you what it is.


sorry you guys had such a beef with me over the value of the 500e
I'm not a bad guy and hate to see another member get sent down the wrong road of repair if I can offer a little help.

if after the proper checks do show the cis box and you are in wa. give aurora auto wrecking a call they have or can locate a tested box for you.google them they are on the web and have a 800 toll free plus they list recent inventory and tons of parts.
hope this helps

appatula

Great post ^

Benz260Benz

Its not blinking, like steadily blinking, its more of an occasional flash and sometimes stays on for a bit then goes away, then blinks once, then comes on solid again, then the car dies, then its on when I turn the car back on and its idling really low and rough, then it goes away and is idling just fine, then blinks again and the car dies again, then I turn it back on and it runs great kind of thing. It's really intermittent so it was hard to diagnose, I know it spent 2 months at the dealership and they couldn't find anything, then 2 weeks at one shop, then I finally found a Mercedes specialist and it took him about a week to narrow it down to the box or the crank sensor; but he was pretty sure it was the box.

I'll definitely check Aurora for more parts because there are a couple more things that need replacing.

appatula

yeah go for the box! please make sure you let us know if that does the trick too!

Benz260Benz

I definitely will! And I really appreciate all the feedback I got on this, I’m totally new to this awesome world of Mercedes but very eager to learn as much as I can. If there are any other ideas that people might have I’d love to hear them. It seems like there are a lot of cool people on this forum, and I’m glad to be a part of it.

YNVDIZW124

No codes on these cars...

If i had to guess on what it is....I would say the fuel pump or the ignition module thingy i forgot the name but it's next to the ABS box and on top of the coil....

ohlord

it's an 88 with obd1.doesn't it have the x11 multi pin port in the engine bay for diagnostics?our 88 735i does,odd!
you know the old system that showed numbers like 1-15 or so.
check for the port,it may take a dealer or some old school tech to run the jumper wires and retrieve the numbers.
If not I will defer to YNVDIZW124 and the check engine light and limp mode that it is triggering will have to be tracked down through a different path.Crank sensor going bad will at times trip the light and cause misfires resulting in low speed stalls and hard starts till cooled on the m103 it can be cleaned or replaced from autohausaz.com 40 bucks.Some sensor in the system is triggering the light and from what you describe it is intermittent and it is being reported to kick in the limp mode, so I would try to rule it out first before the box.
northwest auto wrecking in seattle also has some ecu and assorted mercedes parts so you may want to compare prices between the two.
I really thought it had the x11 port and you could pull the old time numbers.
shame to have it down for so long

shadowgriffen

This is veryinteresting please keep us posted, for all we know there could be a few of us thinking that ours cars are Sloths when in fact there could very well be a glitch in our systems.

i'm going to check mine out as well! (box)

YNVDIZW124

I was wrong since it does have a 8 pin diagnostic plug by the Ignition module but most mb mechanics i know don't want to buy/make the tool to read them. A multimeter can be used to measure the duty cycle of the EHA valve and the oxygen sensor too. All the codes should be in the mercedes repair/owners manuals.

so yes it does have codes but not like newer obd-II cars where you get a number back from the computer, instead you get blinking lights.

http://www.bentleypublishers.com/gal...&galleryId=549

Benz260Benz

Hey guys so i got the ECU and now i'm wondering if it's something i can install myself like a pulg and go or does it need to be tuned or configured by a computer or other tool which my mechanic would have to do?

appatula

Plug and Play! The box will be behind your battery, just unclip the connector, then swap, put connector back on. Let us know how it goes!