Engine missing

[gina2201]

All I can relate the sound to is a valve bounce when it does misfire. That's what it sounds like to me.

 

[Dieselman]

Ok, so results;

At idle: 2.44 v
2000 rpm: 2.7 - 3.0 v
3000 rpm: 3.5 - 3.6 v
4000 rpm: 3.8 - 4.0 v

Does this sounds about right? What does this tell me? Thanks all.

Is this in neutral or when driving.?

Probably about right for a no load situation, a bit low for under load.

Normally to get a reading just trap a wire under the connector as you push it together.

The reading for idle seems a bit high, but the rest seem about normal.

Does the engine misfire if you just floor it in gear from low speed or only when changing gear and is this only after revving hard in the lower gear?

What happens if you just run it hard up a longish hill, does it run Ok then start to judder or run Ok all the way.

If the MAS is oily looking is will reduce the reading, best cleaned. What air filter is fitted, hopefully not a K&N type.

 

[gina2201]

Is this in neutral or when driving.?

In neutral.

Probably about right for a no load situation, a bit low for under load.

Normally to get a reading just trap a wire under the conenctor as you push it together.

The reading for idle seems a bit high, but the rest seem about normal.

Does the engine misfire if you just floor it in gear from low speed or only when changing gear?

Yes it does!

 

[Dieselman]

Straight away, then clears as the revs build or continues to stutter.? What about the long hill test.?

Is it stuttering or holding back and coughing/spitting back.

 

[gina2201]

Straight away, then clears as the revs build or continues to stutter.? What about the long hill test.?

Is it stuttering or holding back and coughing/spitting back.

Yes it does feel like its holding back and spitting back.

From a stand still it will misfire early on when cold, once worked through and you change gear it is likely to do it again, more when you're accelerating hard, not when you change gear at lower revs.

Long hill test? Explain....!

 

[Dieselman]

Drive up a long hill in gear. If it runs OK to start with then gets worse and worse, it's fuel starvation.
Spitting back sounds like too lean a mixture, injectors, MAS, fuel pressure.

Stick any similar Bosch MAS in from another car as a test, it should eliminate the MAS even if it doesn't run perfectly.

 

[gina2201]

Drive up a long hill in gear. If it runs OK to start with then gets worse and worse, it's fuel starvation.
Spitting back sounds like too lean a mixture, injectors, MAS, fuel pressure.

Stick any similar Bosch MAS in from another car as a test, it should eliminate the MAS even if it doesn't run perfectly.

I can't do this latter suggestion anymore....don't have the opportunity to borrow a MAF now.

It's ok up a hill as far as I can remember. Purely when driving from cold it's grouchy and when putting your foot down.

 

[Dieselman]

It's ok up a hill as far as I can remember. Purely when driving from cold it's grouchy and when putting your foot down.

What about when hot.?

If just when cold suspect the temperature sensor is going duff so not telling the ECU to richen the mixture accordingly.

As for the MAS, just any MAS with the same pin configuration, preferably from a petrol engine, should work well enough for a test.

You're only going to ask, so..

Item no 23.

http://www.detali.ru/cat/oem_mb2.as...GM=717.460&CT=M&cat=19K&SID=15&SGR=120&SGN=05

 

[gina2201]

What about when hot.?

If just when cold suspect the temperature sensor is going duff so not telling the ECU to richen the mixture accordingly.

As for the MAS, just any MAS with the same pin configuration, preferably from a petrol engine, should work well enough for a test.

You're only going to ask, so..

Does misfire when hot too but when putting foot down rather than at lower revs.

 

[Dieselman]

Sounds like a lean mixture. Only three things really control that; MAS..seems to be OK, although it would be interesting for someone else to meter theirs as the idle voltage definitely seems high, Lambda sensor (could be), water temp sensor (could be).

Try a run with the MAS disconnected and see whether it's different. The ECU should adopt a generic map, which may run a bit flat but might not misfire.

 

[gina2201]

When you mention disconnected do I just remove the connector and drive it like that? And my measurements are probably not as accurate as they could or should be!

 

[Dieselman]

Yes, disconnect then drive. The measurements were good enough.

 

[gina2201]

Yes, disconnect then drive. The measurements were good enough.

Ok, will try that tomorrow then. Thanks DM.

 

[94mattda]

I love it when you talk techncal DM....can the maf off of my car be used...or do i even have one ....

 

[Dieselman]

I love it when you talk techncal DM....can the maf off of my car be used...or do i even have one ....

I'm pleased you said technical there.

That depends on the age of your car and the injection system used.
If it's a mechanical KE-Jetronic then no MAS at all, if it's LE-jetronic then one is by the throttle valve, if it's Motronic then it's remote in the intake pipe...BUT...both types have a different connector type to Gina's car.

A Bosch MAS with the straight 5 pin connector should work, not ideally, but should work enough as a test.

If we can get the resistance values or voltage feedback for the temp sensor and Lambda probe they can be tested too.
iirc the Lambda is 0.45v feedback. Would need to check that.

Anyone got more info.?

 

[janner]

I have a spare MAS that you can borrow but it's off an E320/E36. Part number0280217500. Not sure if it will fit, maybe DM knows?

 

[Dieselman]

Is that the round plug type, if so..no go. That would fit on the SL300 though.

 

[janner]

After a quick google image search..
Mine looks like this...

Hers looks like this...

So it's a no go. Why do they make so many different types?

 

[Dieselman]

They are generally all the flat connector now, round ones were older Bosch ones.

 

[gina2201]

Disconnected the maf today. Idled fine but when I went to pull off the revs dropped almost cutting out and couldn't drive it like it. Had to plug it back in!