Injection Quantity Variation

[rji]

I was given a copy of the diagnostic log for my car (1.6 TDI). The injection quantity variations were:

Cylinder 1 injection quantity variation -0.3019 mg/stroke
Cylinder 2 injection quantity variation +0.7279 mg/stroke
Cylinder 3 injection quantity variation -0.1727 mg/stroke
Cylinder 4 injection quantity variation -0.2789 mg/stroke

Are these variations set on the fly by the ECU or are they the fixed settings calculated from the injector's IMA code.

Is it normal for one of the variation amounts to be so different from the others?

 

[James_R]

is there a problem with the running of the car?

 

[rji]

Very bad fuel consumption and noise from engine when under load and on occasion when idling. But dealer says there's no problem.

 

[James_R]

Judging by the look of those figures no2 injector is overfuelling causing diesel knock.

 

[techie]

Yeah agreed, they should at idle be all in the minus range, if one is higher it's compensating for something. I'd swap injector 2 and 4 to see if the problem moves.

 

[rji]

Yeah agreed, they should at idle be all in the minus range, if one is higher it's compensating for something. I'd swap injector 2 and 4 to see if the problem moves.

Thanks for the replies. But I don't think the dealer will be swapping anything. They didn't find any faults so they say there can't be anything wrong.

The log says the engine speed was 782.50 rpm (idle). Is the "injection quantity variation" only used at idle? I assumed the variation amount was fixed and used at all revs.

If swapping injectors moved the problem would it indicate a faulty injector or something else being wrong. I appreciate it has to be guesswork but I wanted some ideas from people who know more about it than me. And I won't be taking a spanner to anything myself.

 

[James_R]

If the injector quantities alter (if and) when the injector is moved it points to the injector and rules out that cylinder for faults.

 

[rji]

Thanks. I hadn't considered a cylinder fault. I was only thinking about problems with the high tech stuff.

 

[rji]

I think I can get a VCDS cable to check the "injection quantity variation" amounts with the engine running. Can you suggest any other fields that should be looked at.
Thanks

 

[rji]

The situation is worse than was indicated by the static values taken from the dealer's diagnostic log print.

Using a VCDS interface cable I recorded "Injection amount deviation" for all cylinders plus the crankshaft speed.

Cylinder 1 always has negative values.
Cylinders 2, 3 and 4 almost always have positive values.

Approx 1,150 rpm, 30 mph, 4th gear with cruise control.

Approx 1,150 rpm, 30 mph, 4th gear with cruise control.

Most of the run, approx 10 minutes.

If all cylinders should have negative values and look like Cylinder 1 then it looks bad. Any ideas what might be wrong?

 

[James_R]

Have you checked if there are any outstanding software updates or recalls on your car?

We were replacing a string of 1.6 cr ecus at one point and there was a new software bulletin almost every week for them.

 

[techie]

Yeah at Skoda we have had a lot of updates for the 1.6CR

 

[rji]

Have you checked if there are any outstanding software updates or recalls on your car?

We were replacing a string of 1.6 cr ecus at one point and there was a new software bulletin almost every week for them.

The engine ECU was updated with Version 8811 on 1st April 2011. Nothing changed except the recommended gear display.

I've never heard of any recalls or ECU replacements for the SEAT 1.6 TDI CR. If there are any they are keeping it to themselves.

This complaint has been ongoing since December 2010. The dealers and SEAT refuse to accept that anything is wrong.

EDIT:
What was the date when the ECU's were being replaced?
What was the date of manufacture of the cars that required the ECU replacement?

 

[rji]

REPOSTED - The VC-Scope chart images in Post #10 have been replaced with photobucket images because the original images were not displaying:-

The situation is worse than was indicated by the static values taken from the dealer's diagnostic log print.

Using a VCDS interface cable I recorded "Injection amount deviation" for all cylinders plus the crankshaft speed.

Cylinder 1 always has negative values.
Cylinders 2, 3 and 4 almost always have positive values.

Approx 1,150 rpm, 30 mph, 4th gear with cruise control.

Approx 1,150 rpm, 30 mph, 4th gear with cruise control.

Most of the run, approx 10 minutes.

If all cylinders should have negative values and look like Cylinder 1 then it looks bad. Any ideas what might be wrong?

 

[rji]

I have also discovered the car has recorded:-

ESI: Oil quality 229 = poor oil quality

The oil level has risen rather than fallen so I'm assuming it's getting contaminated with diesel fuel.

Does anyone know how the quality of the oil is checked by the car's systems and what quality descriptions can be recorded?

How serious is it that the car is indicating the oil quality as Poor?

 

[rji]

It's all gone very quiet out there. No comments, anyone?

 

[silver surfer]

oil quality poor could mean its set to time and distance servicing not longlife.A few months ago i had a polo 1.6 cr with the same problems as your at work sent injector mvb off to technical VW and they told me to remove injectors and send pick of injector tips .Sent pick and they told me to replace injectors .Don't be fobbed off keep complaining and something will be done .

 

[rji]

oil quality poor could mean its set to time and distance servicing not longlife.

I guess that means the oil quality is not actually being measured in any way by the car and it's nothing to worry about.

A few months ago i had a polo 1.6 cr with the same problems as your at work sent injector mvb off to technical VW and they told me to remove injectors and send pick of injector tips .Sent pick and they told me to replace injectors .Don't be fobbed off keep complaining and something will be done .

It's booked in to be seen again but I expect just another fobbing off. It is SEAT not VW that we are dealing with. I'll see how it goes.

Thanks for the reply

 

[silver surfer]

ring customer care for seat and give them some stick .vw and seat technical have all date relating to known and common faults and some dealers dont know about

 

[rji]

ring customer care for seat and give them some stick .vw and seat technical have all date relating to known and common faults and some dealers dont know about

Sound advice and thanks, but...

We've complained to dealers, to Customer Care, we've written to the MD of SEAT UK and had several conversations with a Customer Relations Manager for the Executive Office and it's all getting us nowhere. It's an insult to have the first written reply treat 4 months of complaints as an enquiry and ignore all of the issues raised. "Whilst I am sorry you remain unhappy...". Sorry my

They put a PR guy on the case with no technical knowledge whatsoever and hope that you'll get sick of the fobbing off and give up. During these conversations we have both made it very clear that we are not going to be fobbed off with a PR exercise.

The dealer said they would have technicians from the SEAT Technical Unit examine the car but SEAT has refused. Because, they say, the master technicians in the dealerships have the same training and ability as the technicians at Milton Keynes. Telediagnosis will be used but the PR guy can't explain what SEAT teledianosis actually means.

DTC codes - "With no fault present on the vehicle there is nothing we can do". Explaining the problems is useless because the PR guy has no technical knowledge and customers are not allowed to talk to the technical unit. We have only just discovered the problem revealed by the injection amount variations but I'm sure it's going to be dismissed with "the computer says no".

There was a time when a drop in fuel economy indicated that an engine had a problem. But that was before the car itself had a computer telling you otherwise.

Sorry for the rant