Problem Help Required!

[Dave]

A friend Marc has a GX 1997, had problems with it before and got it put up on a MUT II and they came back and said that the problem was airflow.
he has since replaced the airflow sensor and the problem has returned!

basically it loses power, does it on idle and also when driving so that rules out stepper (in my head anyways)!

got it put up on the MUT II again today and they reported that it was the air flow again!!

he got the airflow sensor from Ricerocket, so we know that it was a proper unit and it seemed to sort the problem for a few weeks!!

is it dodgy wiring or something???

any ideas are much appreciated cos Marc is loosing all faith at the moment!!

[MAC 1]

You might know this already but the wiring loom to the steeper is a favourite to fail. Most commonly the green wire for some unknown reason disintegrates. It could be as simple as that. Also, have you checked to make sure the air filter is not clogged up? You'd be amazed how much a dirty filter hinders performance/driveability.

Got to be worth a tryas they're both easy to check.

[Dave]

stepper only really kicks in when idling so if he's loosing power when he's driving that sort of rules it out!
as for the filter, he had an induction kit on there, an itg, we've changed it back to the original to see if it was that and the same symptoms are there!!

[kevinod]

Can you check the continuity to the airflow sensor? that would help check the wiring and maybe back along the line, or is it just directly attached to the ECU?

Damo is reporting what sounds like similar problems, he's replaced the crankshaft position sensor and camshaft position sensor I think...

[Damo]

Sounds a lot like the trouble i'm having, the MUT II told me Crank and Cam sensors, I've changed those and same result as well. Losing my nut at this stage mine is a GX as well. I'll bet the same thing is wrong with both whatever that is.

[Dave]

he's taking it to a diagnostics dude that said he'll be able to tell if it's a wiring problem etc etc! so we'll see!!

[Damo]

he's taking it to a diagnostics dude

Where is he taking it Dave, I'll probably have to do something similar?

[Dave]

A place in Sallins i think, i'll hold off posting his details and all that and wait to see if he can actually sort the problem out, but according to this guy he said that the MUT-II isn't sufficient for testing problems, it'll only point you in the right direction, it won't give accurate results as to what exact parts are gone because all it does is measure volts etc!

he charges about the same for the MUT-II, around €60 or so!

[CJ]

it won't give accurate results as to what exact parts are gone because all it does is measure volts etc!

I think it does a lot more than that, as well as reading ECU diagnostic info, it talks to all of the engine and ancillary various sensors to enable the user to spot problem areas.

CJ

[Dave]

i was just going by what this guy told Marc

[CJ]

i was just going by what this guy told Marc

I wasn't quoting you directly Dave, just thought I'd clear up any confusion

CJ

[Autofix]

Hi all,

Mark, the man who owns the car this post is about, suggested that I register to have a look around, so here I am

I am the diagnostic specialist who is mentioned further down. I think I have been mis-quoted somewhat, so I thought I would do a post and explain a few things. Also I am interested to know how Mark has got on since.

Firstly, if a fault is not present when a car is being tested it is difficult or even impossible to find the fault. When Mark brought his car in the symptom had vanished. Now I could spend hours testing bits that are working correctly and never reach a conclusion but that would not help the customers pocket much and would not be what I consider an honest and professional approach. In a case like this I think it is better to wait until the symptom is present. In Marks case, he mentioned to me that the car was noiser than normal but it sounded when driven like it had a sports back box fitted so I didnt pay much attention to that. Later it dawned on me what could be wrong so i got Mark to return. A small amout of testing later and i think we had a solution.


This brings me to the main reason I posted.

<< he said that the MUT-II isn't sufficient for testing problems >>

Not quite what I said, but not too far off the truth. What I was getting at is that the scan tool on it's own does not fix cars.
There are 3 things required to diagnose faults on modern control systems, knowledge, information and equipment. In other words a technician must understand how the system works, must have access to the informatiom and data on the system and must have the correct equipment to test with.
Any scan tool will give fault codes. These fault codes are, in most cases, nothing more than an indication of a direction for a diagnosis. The MUT, and other tools also give access to live data from the ECU but this is only any use if the guy holding the tool understands what this data means. Also there are other tools that need to be used, like a vac gauge, gas analyser and most importantly, an oscilloscope.

Unfortunately, a lot of technicians engage in what I call "bolt on diagnostics". This, I feel, is because a lot of them do not know how to test the systems. Every now and again it pays to try a part as it can be quicker than testing but in general the final bill will be a lot lower if only the faulty part is changed.

BTW, good looking forum.

Hope I didnt intrude but as you may have guessed this is a subject I am passionate about

Regards

Alan

[CJ]

Hope I didnt intrude but as you may have guessed this is a subject I am passionate about

Not at all Alan, I think speak for a lot of people when I say that its refreshing to have a professional opinion on the forums from time to time.

I would be interested to know where you're based and some details about the business, it would be useful to have the service of diagnostic specialist on hand when a member needs a professional opinion in the event that traditional fault diagnosis fails to reveal the source of a problem.

CJ

[steelroe]

Alan,

Interested to know what diagnostic system you are using to access the FTO systems.

[Autofix]

Hi CJ

My business is mainly diagnostics (about 70%), based in Sallins, Co. Kildare, but with some service and repairs for long established customers only. I also have some involvement with various European based equipment companies and I sell a nunber of scan tools.
In general I do not see a lot of FTO's but I would be happy to answer any technical questions or give advice if needed. The only problem could be getting me to answer the phone as I am always busy so if need be leave a message and I will call back or even better e-mail.

Hi Steelroe,

I have access to various systems but the one I find best for Mitsubishi's is the Carmanscan.

Regards

Alan

[Dave]

Alan,
Marc got the exhaust fitted at the weekend!! i must ask him has it cured the problem!! i'll let you know!

Dave

[Autofix]

Hi,

In case anyone is interested, I spoke to Mark about this in the last few days and the new exhaust did fix the problem.

At the time he had a code for the air mass meter but in reality the code was just pointing to an airflow problem. Testing the air mass figures (signal) did not show any problem. The exhaust was blocked and so caused the engine difficulty breathing. The amount of air being inducted was lower than the ECU expected, hence the code.

Regards

Alan

[prestigejs]

Alan has made very good sense talking about diagnostics and is very correct in what he has said.

One of the best systems around that we have at present is the Snap on scanner with the Japanese import and troubleshooter cartridge and the picoscope oscilloscope, however unfortunately between the two they are one of the most expensive options on the market, but as Alan said the main thing is having a technician that can use them.