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Billy
Billy, Trainer/ Master Technician
Category: Car
Satisfied Customers: 3498
Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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Hi Ive got a Suzuki Grand Vitara 2008 1.9 diesel ddis - Ive

Resolved Question:

Hi I've got a Suzuki Grand Vitara 2008 1.9 diesel ddis - I've had the dpf removed and the ecu remapped, this was to fix a fault related to a non-clearing dpf unit.

Since then I've had a problem with the car dropping into limp mode when the engine is under load - this is intermittent but easy to replicate under certain driving conditions. This has been happening now for about 2 months with no ECU codes being displayed.

So far I have had most of the major sensors replaced, a new turbo, a new intercooler and a new MAF. There was a pressure leak detected in the intercooler and this was thought to be the cause but on the way home from the garage the fault happened again.

Switching the engine off and on again clears the limp mode every time and the car resumes as normal. Obviously I have very little confidence left in the car and am running out of ideas as to what is causing the problem...
Submitted: 3 years ago.
Category: Car
Expert:  Billy replied 3 years ago.

nabilc :

Hello and welcome! I'm Billy and i will assist you with this.

nabilc :

To me, it seems that the ECU program you have is causing this. As getting in limp home without any codes is not proper ECU operation.

nabilc :

Did you check the ECU program, maybe there's an update, a different version etc..?

Customer:

Hi, sorry for the delay in replying - the ECU was checked and deemed not a problem. The boost limit was tweaked on the ECU and as per ususal nobody has been able to replicate the fault.

nabilc :

Hello,

nabilc :

So the fault is no longer occuring? (as you are saying that it cannot be replicated)

Customer:

The fault is still occurring - nobody else has experienced it. I've made sure that the engine is warmed up in the morning and done the normal trip into work and it goes into limp mode on at least one of the hills coming into the office. It didn't do it yesterday but this morning it did, 30mph, 4th gear, about 2000rpm (give or take) - I've just been out over lunch and tried to replicate it but it went fine - no problems. I'm running out of ideas and although the garage I bought it from is being very helpful and trying to fix it (thankfully still under warranty) I sense that they are running out of ideas too.

nabilc :

Hello,

Customer:

Hi

Customer:

Sorry I missed you before

Customer:

Any ideas?

nabilc :

The hardest problem to trace would be the intermittent one.

Customer:

And the fact its not registering any error codes

Customer:

makes it that little more complex

Customer:

We can narrow it down a little

Customer:

It does seem to do it first thing in the morning and if the car has been standing for some time

nabilc :

The only thing that can be done for now (without replacing or checking parts at random), would be waiting for the problem to become more frequent, so it can be replicated, and then connecting a scan tool (diagnostics computer), and reading the live data while the problem is occuring, so the components (sensors, actuators etc..) can be monitored and the culprit confirmed, to replace accordingly.

nabilc :

only in the morning, just when you start it?

Customer:

I start up and normally get it on the first hill on the way to work

Customer:

If I crawl up the hill well under 2000rpm I'm okay

Customer:

But then I get it on the second hill by which time the engine is warmed up

nabilc :

within 5 minutes of starting the vehicle?

Customer:

If I go over 2000rpm pretty much yes

nabilc :

within 5 minutes of starting the vehicle? (max)?

Customer:

I can start the car, reverse out of the drive and then straight up the hill - less than 5 mins

Customer:

Thats on hill one, if its the second hill its probably about 10 mins

nabilc :

you get the problem most frequently on the first or second hill?

Customer:

first

Customer:

I only tend to get it on the second if I've not had it on the first

nabilc :

ok........i would check for a mild exhaust leak, before the turbo.... so the leak would be on the exhaust side, between engine and turbo. This would close when the exhaust warms up and metals expand.

Customer:

Would this not trigger some kind error code?

nabilc :

not always...

nabilc :

It is worth a check...

Customer:

Definatly!

nabilc :

and it will increase in frequency, as the crack widens....

Customer:

Anything else beyond that it could be?

nabilc :

If the theory is correct.... it is logical, and would cause the exact same thing, but it needs checking and confirming.

nabilc :

beyond that, i would check the cylinders' compression, and check if you are not getting any mild leaks (from valves most likely), when engine is cold.

Customer:

okay, is there anything I can look for to see if there's an leak?

nabilc :

on the exhaust side (between the engine and turbo), you can use a heat gun, or a smoke detector, when engine is cold... on the engine itself, only a compression test will give a clue...

Customer:

I'm guessing a heavier load on the engine would cause this limp mode to kick in fairly quickly

Customer:

hill number one is about a mile straight up and very very steep

Customer:

Its just an ecu specialist had it for a couple of days this week in a similar rural area (doubtful as steep) and had no problems

nabilc :

exactly... the heavier the load, the more pressure you have in combustion chambers, and in exhaust....that is why a leak sounds logical...

Customer:

its also parked on the street and not under cover, which I'm guessing will chill things a little more

nabilc :

it will... however, it would not add much to the problem if you already have a leak...

Customer:

I'm just trying to factor out why other people haven't had the same issue

nabilc :

indeed, this is a good way of diagnosing, eliminating factors...

Customer:

I have on occasion had it on the way back from work so again it will have sat outside for 7 hours but I either get the problem within five mins or about 10 to 15

Customer:

which is actually about the same sort of time from leaving home in the morning

Customer:

so it could explain both ways

nabilc :

indeed.... both (leak theories) are worth a check in my opinion... that's what i would do, if i had the vehicle...

Customer:

I'll speak to them on Monday and also time it going in and coming out - see if it makes sense.

Customer:

Thanks for your help

nabilc :

You're most welcome...

nabilc :

Best of luck... and get back to me if further assistance is needed on this....

nabilc :

Frustrating as it is, it is interesting.

nabilc :

Thank you for your trust! Get back to me if you need more assistance...Thank you in advance for the positive rating...
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Billy, Trainer/ Master Technician
Category: Car
Satisfied Customers: 3498
Experience: Trainer 8+ years, master tech. 10+ years, SAE member
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