Injectors 2 and 3 not working.

[igreenrover]

Hi

Had some trouble last weekend, the car started to miss-fire. When checking I broke one of the leads and so decided to get some new plugs and leads.

After replacing the leads and plugs today, I still have a miss-fire. Further checking reveals that injectors 2 and 3 are doing nothing.

Anyone any ideas? I'm really lost.... ECM?

Gareth
89 SE

[igreenrover]

Hi again guys...

Have just removed the ECU and the underside of the board appears to be rippled (bubbled) on some of the wider tracks. The entire unit is like this although its clean and appears in new condition otherwise.

Does anyone have any experience with these systems? Although I'm doubtful, is this correct?

????????

[sanj]

igreenrover said:

Hi again guys... Have just removed the ECU and the underside of the board appears to be rippled (bubbled) on some of the wider tracks.

The bubbling is normal, it is just the soldermask or the conformal coating.

Cheers,
Sanj

[Lasse]

Hi!

Did you give your engine bay a wash recently? Actually I dont have a clue.

I think I would start checking electrical connectors for oxidation, moisture etc. One of my collegues in Sweden couldn't start his V8 the other day because he had oxide on one (1!) of the engine earthing points. So it seems rather sensitive...

The harness for the injectors is connected via one big connector in the rear of the engine bay. Of course i would also check the connectors on the injectors (but I guess you already did that. After that the next connection is the plug into the ECM...

By the way, how did you conclude that the injectors do nothing. I mean there is really no easy way of seeing if they operate or not?

Best Regards /Lasse

[igreenrover]

Thanks guys.

I have washed it, but this was after the problem!
Pulled all the connectors I could find and checked / cleaned them. Checked the continuity between the ECM plugs and all the injectors – no problems there. Also checked between the fuel pump relay and the other side of the injectors, again no problem.

Lasse, if I run the engine and pull the connectors for injectors 2 or/and 3 there is no change, its just running on just two cylinders. If I pull the connectors for either 1 or 4 the engine stops almost immediately.

BUT

If I put a connector from Injector 1 or 4 onto either 2 or 3 (or both) then the engine runs about the same. So I guess that injectors 2 and 3 are mechanically working but are not getting a signal from the ECM - right?

If this is any help… at first the engine would run fine and then suddenly switch to 2 cylinders… then back to 4 for a few mins, then back to 2, and now ONLY 2

[sanj]

It seems much more likely that you have a bad coil, as 2 and 3 share the same one. I have seen where a bad plug wire eneded up damaging the coil as well, with the results you describe. Although Lotus specifies only a single part number for the coil pack assembly, the coils are standard GM parts and can be replaced separately.

Cheers,
Sanj

[igreenrover]

sanj

Thanks, but if it were a bad coil then I think that changing the order of the injector connectors would not improve things?

For example:
If I take the injector cable away from no 1 and instead plug it into no 2 then no 2 fires fine. I can actually change the injector connectors so that both No 1 and No 4 feeds from the ECM are instead connected to injectors 2 and 3, 2 and 3 then fire okay, but 1 and 4 don’t work with the supply from 2 and 3.

All I have is a circuit diagram. I can trace the cable from the ECU plug to injectors 2 and 3. It's a black and pink cable. All 4 injectors are supplied by a common loop from the fuel pump relay (its Orange and White cable) and this feed is getting to all 4 injectors. I don't have any way to test the output from the ECM as my scope is shot!

[sanj]

igreenrover said:

sanj Thanks, but if it were a bad coil then I think that changing the order of the injector connectors would not improve things? For example: If I take the injector cable away from no 1 and instead plug it into no 2 then no 2 fires fine. I can actually change the injector connectors so that both No 1 and No 4 feeds from the ECM are instead connected to injectors 2 and 3, 2 and 3 then fire okay, but 1 and 4 don’t work with the supply from 2 and 3.

I'm a bit confused by the test you are conducting, please bear with me. Are you saying by switching the connectors that you are now firing the #2 injector when #1 is supposed to be firing? If true, what result makes you feel #2 is firing properly when you do this? If nothing else, I'd think you are firing the injector at the wrong time. You may be able to obtain a test lamp that plugs into the injector harness which will illuminate if the ECM is trying to fire the injector, they are readily available at auto stores in the USA, not sure about over there.

I still feel that you should check the coil. Get an extra spark plug and connect the #2 ignition lead to it, being certain the body of the plug is earthed. Check for spark. Do the same with #3. If you have spark on both, then the coil is likely OK. Either way, measure the resistance in ohms of the 1-4 coil across the terminals where the ignition leads plug in, then compare to the 2-3 coil resistance reading, they should be substantially the same.

Cheers,
Sanj

[igreenrover]

Hi Sanj

Yes, I appreciate that when I swap the connectors around like this that the injectors will be opening at the wrong time, but when the engine is running at less than 1000 rpm the timing is still close enough for it to run. The only experience I have with electronic injection is on my Range Rover. In this case there are 8 injectors and they fire one bank of 4 at a time (left then right etc…) so I guess that at lower RPM (OK, very low!) then it’s not so critical.

I agree that doing it this way wont tell me that the injector is working “properly’ but it does tell me that if the injector receives a signal to release fuel, then it will work, and it also tells me that it’s working ‘enough’ to ‘run’ the engine. All I wanted to know was “If the ECU sends a signal to this injector, will it allow fuel to pass”

As you suggested, I’ve checked by using a spare spark plug and all four do appear to be fine. I will try measuring the resistance across the coils as you suggested though tomorrow, will report back.

I was glad to hear that all the boards appear like mine though…

Thanks again, please bear with me!

[igreenrover]

Hi Guys

Just heard form the ECU guy that my brother uses. He says that as its a USA Specification unit, he cant check it! Also he can’t recommend any place that can!

Anyone know of a place in the UK that can do this or do I need to go to a Lotus dealer?

[rfoster]

Give Steve Roberts at SJ Sportscars a call - one of the most knowledgeable people in the country on Lotuses - I'm sure he could help you & supply whatever you need. 01363 777790.
Cheers, Richard.