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Discussion Starter #1 (Edited)
1990 Graduate w/Motronic

I've been fighting with my fuel system for several seasons. Specifically, I have regularly replaced the relay next to the ECU. Historically, that has helped for a short time. After a month or so, I had a no start problem again.

A buddy and I have been looking at everything in the fuel and ignition system to try to track the problem down. We found that the fuel pressure regulator had failed and replaced it. Fuel pressure is good, and all of the plugs are getting spark and fuel.

We replaced the distibutor cap which had the little plastic knob at the top/inside of the cap broken off. With this, the car runs. Unfortunately, it doesn't run well. We didn't replace the rotor.

Two new problems: 1. It sounds like it is missing. The idle is really rough and it doesn't even out under throttle. 2. The tachometer is bouncing all over the place -- it jumps to north of 3K and bounces from 3 to 5K wildly.

Since I have a historical problem with the fuel relay and I understand that the tach is run off the ECU in Motronic cars, I am thinking I may have a failing ECU.

Any thoughts would be appreciated. I have pulled the ECU to get it tested and if necessary replaced. Before I spend $400+ on a new ECU, I thought I would lean on the collective wisdom of the BB.
 

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We replaced the distibutor cap .... it doesn't run well. We didn't replace the rotor.

Two new problems: 1. It sounds like it is missing. The idle is really rough and it doesn't even out under throttle. 2. The tachometer is bouncing all over the place -- it jumps to north of 3K and bounces from 3 to 5K wildly..
A bad rotor or one that doesn't match the cap its combined with can cause all sorts of odd things to happen.

Might want to deal with that first to see if it has effect before spending many duckies on ECU work.

EDIT:
And double check the plug wire sequence while right there.
 

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Before sending the ECU to a ECU specialist I would as a last resort have a Alfa specialist check and tune up the ignition and fuel system.
As others have stated even the smallest of fault or wrong part can upset engine running.
Erik
 

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in reality the Motronic ML4.1 ECU rarely gives a problem - If I think of the hundreds of posts on here regarding rough running, or no running alfas, maybe only 2 or 3 times only it has actually been the ECU.
When you say you have constantly changed out the relay next to the ECU, which one, there are 4 back there?
You mean the one with the red stripe (Motronic Relay with diode) or the Fuel relay (normal Sipea) or one of the others?

-------you say a 90 spider with Motronic and you didn't replace the rotor? Was that because it wouldn't pull off? The rotors on the Motronic spiders (90-94) are glued on from factory and you have to break them off - to do this you have to pull the distributor (easy, one nut holds it in) and crack off the rotor (remember which way the rotor is pointing, so you put the distributor back in the right way around, as you can inadvertantly put it back 180° out). The rotor for the Motronic is different to earlier spiders and I would only go for an original Bosch cap and a Bosch rotor - (rotor# Bosch 04168 / distributor cap# Bosch 1 235 522 056) - needless to say you do not have to glue a new rotor back on.

That is 20 bucks worth and 15 minute job.......and even if it is not the actual cause, a useful thing to do.
 

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Specifically, I have regularly replaced the relay next to the ECU. Historically, that has helped for a short time. After a month or so, I had a no start problem again.
I don't have my manuals here: is that the relay with the diode or the one without? I suspect if you put a no-diode relay in the location that requires a diode, it will fail quickly due to arcing (and quite possibly damage the ECU in the process?).

Not sure which relay you're talking about, but that's one possibility for the repeated failures.
 

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another thing to cause really rough running (as you do have spark and fuel) is a non functioning VVT and can make the car tick over like a pig! (Variable Valve Timing solenoid, on the front of the cam cover, inlet camshaft side)
The manual (section 00-19) says how to test this:
engine ticking over, pull 2 wires from VVT and connect a 12v battery + and - to the connectors on the VVT itself (doesn't matter which way around). If the VVT is good, the engine should cut out or at least run very rough indeed.
Note: It also has a specific relay near the ECU (one of the sipea 0440 relays, the one with a 10Amp fuse)

A photo of the relays (they can be in different order to the photo, which is from my 1990 S4 spider, but you can see the one with the red stripe clearly, this should only be replaced with one with a red stripe:))
the 4 relays back there are the Main or Auxillary Relay (fused 15A) / Motronic Relay (red stripe, with diode) / VVT relay (fused 10A) / Fuel-Lambdasonde O² relay / ....but not necessarily in that order on other spiders!

PS disregard those odd yellow wires back there, that is for an anti-theft fuel cut-off switch, that has been fitted!
 

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Check that the crank sensor is properly mounted and working correctly. I had the same symptoms (minus the relay seemingly fixing the problem) when mine was loose.
 

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Discussion Starter #9
This is very helpful. For starters, we didn't pull the distributor and replace the rotor. Sounds like we need to do that. Second, my ECU relays don't have fuses. I suspect that is a very bad sign. As for the relay with the diode, I didn't realize that it was different than the others. That could easily be causing part of the problem. I replaced the Crank Position Sensor about 2 years/500 miles ago. I will Ohm it out to see that it is functioning -- I think I saw a thread on that in here somewhere. In any case, the sensor is relatively new. Hope that isn't it.

Any suggestions on a good vendor for the Bosch relays?
 

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On the CPS - did your issues begin before or after you replaced it? If after then first check its mounting. With mine the bolt loosened up and it kept working - if erratically - until it fell off altogether. The sensor itself was fine (not much to it), it was just loose on it's mounting and bouncing around giving an inconsistent signal to the ECU. Mine generally idled fine, but the tach jumping all over the place was a definite symptom.

If your issues started before I suppose it's always worth double-checking, but in general I'd say you've eliminated that as a possible issue.

Chris
 

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Discussion Starter #11
Chris: I will make sure it isn't loose. The tach issues is new; the intermittent ability to run the car is ongoing. Good suggestion.
 

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Just a thought here, can we just make sure the 90 spider you are talking about is indeed the Motronic 4.1?
Do you just have one ECU as in my photo above?...if so then it is....then we are at least talking about the same system:)
(I ask because late L-Jetronic spiders had both a Jetronic ECU and a Motronic ECU!)

AS for the sipea 0440 relays, Vicks Auto list these (EDIT, sorry wrong one!)
but it has an original part nr: 60501199 if that helps - they are out there!

and the Bosch Motronic relay is listed by Rockauto
BOSCH Part # 0332014112

and also several on ebay (fits range rover, BMws etc)...just type the bosch number in the ebay search box.

.......very strange you have no fuses on those 2 relays.............??
 

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to save you searching the CPS test details:
Test is 520 Ohms, or 0.52 K/Ohms from centre plug to one outside connector, other outside to centre gives no reading. (you test the plug coming from the sender itself, by no means should you put an ohmmeter to the harness going back to the ECU.........but that is probably obvious:))
 

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Discussion Starter #16
The unexpected

Here's the update... Both my elderly parents have been admitted to the hospital in the past two weeks. I am probably two weeks away from getting back to the Spider. So much for spring. I'm sure I owe it to them to adjust my priorities.

Thanks for all the great advice thus far. I will be back on the forum (and hopefully the road) when they are on the mend.
 

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Discussion Starter #18
Progress

I may not be able to work on it, but I can buy parts online! I have purchased a new rotor and cap and the relays for the ECU. At least I'll have what I need when I get time to work on her.
 

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I may not be able to work on it, but I can buy parts online! I have purchased a new rotor and cap and the relays for the ECU. At least I'll have what I need when I get time to work on her.
........that's the alfa spirit!:)
seriously though, hope the other "far more important things" go well for you all...........
 

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Discussion Starter #20
Sweet Success

Here's the update...

There was a loose/intermittent connection on the fuel system relay (far right of the four relays at the ECU.) When it connects well with the pins -- boom. The sweet sound of a cam'd alfa motor.

Thank you for all of the great advice. Now, if it ever stops raining, I'll be out on the road with the rest of you.

Thanks.
 
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