94 c280 resurrection, striping, race build

[rwd4evr]

I'm going to pickup a 94 c280 Saturday. It's destiny is to be the replacement for my 84(?) 300Dt race car experiment. I'll call it reasonably successful with a 2nd and a 4th place finish among a couple other top 10 finishes in maybe 7-8 races(of about 40 cars +/-), which are 100 lap(one 150 lap) races with gutted cars and safety equipment as far as you choose to go. I've only run them at one 1/3 mile banked asphalt oval but this car will be built to standards needed for a bunch of local(ish) tracks that run them including a couple dirt tracks. This one gets a rollcage. The W123 handled great but it just has nothing half way down the straights, both of my great finishes were in the rain where power wasnt the top priority. I blew it up pretty bad last race, it was hurt for awhile but kept going with some cooling mods to run with a blown head gasket venting exhaust but not the coolant.

The w123 was great because of the big real metal bumpers, these races are red flag only, no yellows. They stop it for stopped cars in dangerous situations but spins and whatever just happen. It's not a demolition derby but contact is not frowned upon much so it was a great battering ram when someone wanted to get feisty. I'm a little concerned about the fragility of the multilink rear, I bent a couple rear control arms getting into the wall hard and have little faith the multilink would have survived the last one. thats a rear wheel and the view is straight down the side of the car! From what I see on fcp euro it appears the r129/w124 rear control arms are interchangeable, but I've never owned a w202 or taken one apart. I'm hoping the V8 or v12 r129 subframes I have will be a beefier parts source. I have a w140 300se sourced 3.69 diff that should be a minimal mod installation too I've definitely learned that a faster car and a little more caution will be better but it's still going to get slammed. I can box some of the stamped arms if necessary.

It will probably be run as an Auto for the time being but a manual swap is definitely in the works since I'd like to do some other Motorsports(and games ) with it. My biggest question mark is the computers having issues with the swap. Hoping duxthe reads this far and can chime in. One being weather having the shifter in different gears will have any effect on power/tune? I know a guy that 6 speed swapped his 94 e420, im assuming the engine management is very similar, and he had an issue where it had a hickup at 4500 rpm if the auto shifter sensor was in any gear but park. My concern is, is something in the ECU changing parameters and even possibly a reduced power situation even when it "feels" like it's running ok in park with no speed sensor? My car is a non asr according to "lastvin" so that may be a positive as far as the ECU being involved in throttle and such. Any insight on that would be very much appreciated. The other worry is any anti theft BS that might be there. I know about the late 90s early 2000's electronic key, column lock /no start issues but I really have very little non pre 86 car knowledge. I can't have it cutting power or shutting off or something because of, well... Anything. I'll need to have a push button start that will start in any gear, and I don't know if that would throw the ECU or whatever security this thing has for a loop. I don't really do the next gen multilink rear cars for exactly that reason, computers are not my thing. The wiring harness is a concern but I have a hard time believing it was still running a couple years ago with no issues with a candy coated engine harness. The car got parked for a fuel leak and then some **** bag stole the catalytic converter, which is the other issue that concerns me. Will the ECU lose it over the second o2 sensor reading? I found a little mini catalytic converter gizmo that you mount the second sensor in to fool it, I hope that works.

Hopefully none of these issues will be too much to deal with. The rest of the build is getting every ounce of weight out of it and building my first rollcage/mounting a race seat and harness. No glass, no lights, doors bolted or welded shut and some rub rails. I'm hoping I can actually run the aluminum w123 bumpers, I need to check with tech inspectors on legality. Shame it's not a c320(I assume there was a m104 3.2 w202). I do have access to a 3.2 from a w140 also for down the road possibly.



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[rwd4evr]

Sorry I started the thread before I was done by accident. Had to add a bunch more.

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[duxthe1]

A couple of things.....

A 94 should not have any antitheft issues, so no worries there. Also a 94 should not have a 2nd O2 to worry about.

The manual conversion with an auto ecu probably will give issues but I reckon there is a simple fix. I'd simply add a microswitch to the throttle linkage so any time you come off idle, it closes the circuit for the gear recognition. That way its always "in Drive" when you rev it.

Regardless, that'll be a really cool build. Cant wait to see it come together.

[Frank Reiner]

A couple more things -

The 722.4 trans is a wimp; find a 722.3.

Ditch the HFM; find a K-jet manifold from '88-'93, and a K-basic metering unit from '77-'85.

[rwd4evr]

Originally Posted by Frank Reiner

A couple more things -



The 722.4 trans is a wimp; find a 722.3.



Ditch the HFM; find a K-jet manifold from '88-'93, and a K-basic metering unit from '77-'85.

Induction and computer need to be stock for the year of the car/motor. I do have that m104 ke jet intake though, plus a bunch of m110 air meter setups. I don't know how the COP ignition would work with k jet though. I was planning on putting together a 280e with k jet m110 power but it would be a huge build with parts from a bunch of cars to make it legal since I don't have an actual 280e. It would be a diesel 123 with a w126 m110 and all the needed wiring for ignition and injection. Do-able but when this popped up cheap I kinda fell for it, more power, lighter, probably better handling(but definitely not as tough&#129764. The 123 had very limited alignment adjustment too and rode so high stripped down it was out of it's happy range of travel but still did handle really well. I'm kinda using it as an experiment to see if I want to go to a multilink chassis for my next drift car too.

I don't think the 722.4 will be a problem. If it comes out a manual is going in though.

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[rwd4evr]

Originally Posted by duxthe1

A couple of things.....

A 94 should not have any antitheft issues, so no worries there. Also a 94 should not have a 2nd O2 to worry about.

The manual conversion with an auto ecu probably will give issues but I reckon there is a simple fix. I'd simply add a microswitch to the throttle linkage so any time you come off idle, it closes the circuit for the gear recognition. That way its always "in Drive" when you rev it.

Regardless, that'll be a really cool build. Cant wait to see it come together.

Welp....help.... I have a thread in the 202 section on BW(🫤 no pics, format is so crap over there) so i just copied this because it's a lot to write out.

Whoaaaaa baby!! . I bought the car. With the fuel leak and it sitting for years I unplugged the pump and just cranked it to hear all the rods were in it. No bad sounds. Trusted the seller that it ran great when parked. Maybe not a great move. We'll see. Where to start..

Positives. Not really rusty for the most part. Interior is really nice although it's all coming out soon. Engine seems smooth (when all cyl are firing) and quiet (like valvetrain wise, cause the exhaust is wide open). It's moves and stops.

Neg.
Major electrical gremlins. I may have a couple clues.
1. hooked up a battery once I got home after I opened the fuel rail put a hose on it and fixed the fuel leak at the pump. Ran the pump off a jump pack and only a small amount of awful varnish came out. Added 4 gallons. Tried to start it. Missing horribly. Realized the pump was just running no matter what. Found a jumper wire in the fuel pump relay plug...oh boy. Messed with a bunch of stuff, relay is good, fuse in it is good. It's definitely mixed with some stinky crap that didn't pump out though. Probably not helping the missing issue. Plugs

2.Found it's not charging either. Great. Checked an cleaned all fuses with a wire brush to be sure. I've gotten it to run clear for moments then it reverts to 2-4 cyl at this point .Tried testing injector output and got confused by constant power at the plug(then did research and found that's correct).


3. Notice most of the dash lights are on with KOEOff but will blink kinda sporadic. I thought it was code at first but it's not. Only thing that stops it is pulling the cluster fuse. No other circuits or relays seem to affect it. At this point it's running better but still not right all the time. I'm using a big charger on 10 or 40 amp to keep it running. In the two pics one is a single frame of the dumping of the lights. This is engine off just sitting there. Nothing shaking the car, no relays clicking or anything. It will just flash off. While running it will flash on. It kinda seems to do it worse when the charger is off but it's hard to say.


4. I have decided I need to get the alt working and try to figure out the fuel pump relay issue but I noticed there was a small whining sound coming from down near the throttle body I think wouldn't shut off with battery hooked up until I disconnected the engine harness plug from the ECU(I'm pretty sure). Then it didn't repeat after I cleaned up and moved the car off the dolly and jack to its parking spot.

Sooooo. Reading I've done so far seems to suggest voltage regulator could be part of the dash issue and the flash while running(which cuts the tach also) seems to coincide with a stumble or serious cylinder dropping. Also the OVP relay has been mentioned which I'm not certain which one it is in this car. There's a bunch of relays with fuses strewn about under hood , in the back half of the fuse box(need to unscrew the top to get at them) and over by the ECU bank. There was times it would refuse to start and just pop on one cyl but was idling nice and revving ok a lot of the time. I drove it across my lot and parked and it seemed very peppy.
The wiring LOOKS ok not cracked at all, but I'm not sure if it's a replaced engine harnes or not. The MAF plug shows what looks like a 6/97 to me but the tag sure appears to be 26.8.93 (8 26 93 IN AMERICAN DATE ORDER) and the 202 540 4032 number comes up delphi improved design.. I'm going to concentrate on getting the changing system going then move to rural pump relay. The other main issue is no exhaust after the two pipes come together for an inch or two and no O2 sensors. Neither helping for stumbles and stuff. I'm working on figuring out at least a temporary solution for that too. The front O2 plug is damaged so I'll need to address that as well.

🫠 any insights throw my way will be appreciated.



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[rwd4evr]

I would be very open to getting rid of everything including the dash if necessary to just run it on the ECU and engine harness if possible, tons of weight and complication gone. Switch to a pump relay and ECU power. I can get an oil and temp gauge. Tach would be nice but not really that necessary.....thoughts?

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[Tony H]

I say dump it. It was parked for a reason most likely. Keep it simple as possible. Newer cars scare the HE double hockey sticks out of me. I'm going back to carburetors and points like the old farts at the car shows.

[rwd4evr]

Originally Posted by Tony H

I say dump it. It was parked for a reason most likely. Keep it simple as possible. Newer cars scare the HE double hockey sticks out of me. I'm going back to carburetors and points like the old farts at the car shows.

Yeah that's why I don't own anything remotely new. My daily is a 91 but it's mechanical diesel so I don't have to worry about it stranding me. I wish this one was k jet. Hopefully a new voltage regulator/working alt/good battery makes things all start playing nice. I really don't see any cracked or failing wiring anywhere. My CLK55 is really upset by voltage sway. Maybe this is too.

It was 400$ so it's not a loss of any big money. Scrap would nearly cover it. Wheels alone would bring half probably. Lots of good stuff on it.
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[rwd4evr]

I'm far from throwing in the towel on making this a drivable street car to shake it down before it gets the race car treatment but I did a little searching and came up with the ECU wiring diagram. I'm no expert at all but to me it looks like it's a pretty simple (on paper) task to make the ECU run the engine. Anyone want to chime in on this?

Right side is ECU and only 4 wires cross out of the pin out to other places Am I looking at it correct and all it would need is

1. switched hot to the terminal block 15 and a fused hot from there to line 1 blk/red
(I haven't read a schematic in forever and I'm unsure what the dashed line coming off the fuse denotes before it goes back through the EGR valve and to pin 25)

2. What would the signal from the OVP to the MAF sensor be and when? Assuming hot while runnning but would it be switched at all for any reason?.

Here's a non screenshot diagram too.
https://imgur.com/k1BLM

Is it that simple? I have to be missing something right?

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[rwd4evr]

Oh yeah I'm missing something. The left side is the OTHER 44 pin connection on the ECU. I thought it could be fun without it since it's chassis side but the 02 sensors are over there. Still maybe possible with a heavily deleted 2nd harness but definitely more work involved.

If anyone is very fluent in the immobilizer setup on this HFM generation I'd like to hear about it. I have a no signal from the ECU to the fuel pump relay currently and my hunch is that. Someone obviously proves the signal and ground to the FPR already so thats fantastic. No headlights flashing or any crap like that going on, and it runs with the FPR hotwired. My first job is getting the alternator charging, see if that wins me any battles......

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[rwd4evr]

Progress! I swapped the voltage regulator which did nothing for the fuel pump relay issue(not shocking) so I jumped the FPR to see if it was charging now while running. No luck. Then I started digging around the ECU area and saw the OVP had been prayed opened and messed with. I found a test procedure and sure enough it's cooked. Closest one I have is from a 1991 350sd, it's missing 2 pins but only one is used in the car, and the other is power on with key same as the one next too it so I just jumped them together. Here's where it gets weird. With the "new" OVP in the fuel pump relay now works, the car fired right up and seems to be running well. Lights aren't going bonkers on the dash but still no charging. I go to shut the car off..nope. Key doesn't shut it off. It slowed the idle briefly but it stays running with the key off. I don't know if the OVP or the jumping of the relay could have cooked the brand new voltage regulator or more likely the alternator has an internal short that is back feeding or something to keep the car running. I didn't love the idea of disconnecting the battery while running but it was the only option to shut it off. I then took the jumper wire out of the OVP and it still ran exactly the same. No charge and no shut off. I really don't want to because it looks like a pain in the ass to get out but I think I need to swap the alternator.

On another note I vacuumed the small amount of oily crap floating in the coolant resovior out and the coolant color is not very green at all. I drained some into a clear bottle and it's not good. It's looks like murky water with sparkles. I'm guessing some bars leak or block seal crap. Great. Ive got a line on a dirt cheap 94 e320 motor and ECU , the guy bought it for a trans he needs and is parting it but has no where to work to pull the engine/trans, so I'm bartering to get the motor and ECU for the frontend bits he needs to make it roll, and dolly it to my shop after he pulls all the other crap he wants off it, then pull the drivetrain, trans for him, motor for me and scrap the rest. So, as long as I get the electricals doing proper electricalisms in this car with the possibly hurt(ish) engine currently in it will still be a very cheap car even if I gotta swap it. I won't cry about another 30hp and tq either.

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[duxthe1]

The E320 engine probably also needs a head gasket, but you should still do the swap.

[rwd4evr]

Originally Posted by duxthe1

The E320 engine probably also needs a head gasket, but you should still do the swap.

Are m104 notorious head bastards? I don't ever recall hearing that.

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[rwd4evr]

Only played with it for a minute tonight after working on other stuff, but I'm kinda confused˛. No change with the alt wires disconnected. With "the wrong" OVP relay installed it's showing key on power to the small pin with the key off(used a led light with wire stuck in the socket before I installed it). I forgot to just check if there is constant power to the socket key off or if the OVP is actually back feeding it. Maybe the OVP relay schematic I found isnt correct. The older "wrong" one 7 pin and the one I found the schematic for(9 pin same as the correct one) are labeled with conventional relay language, 30 30a 87a ECT. But the correct one is labeled 1-9 with all the same pin spacing and the one small one. Idk. New OVP in bound.

The one positive is that the pretty sparkly strip club hot tub water I drained out of the radiator last night didn't freeze in my freezer so at least I don't think the whole cooling system is stressed cracked ready to explode from freezing. It also seems to be running very well, kinda hard to say with it being so loud but it revs quickly and clean.

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