[tonyevans]

Hi all – I have a 1998 GV 2.5lt V6 which starts great – Idles OK – accelerates well but when I level out for constant revs in any gear it cuts in and out as if someone was turning the ignition or fuel on and off.

I do NOT have any engine light and tested it with Rhinomans magic box and one of the O2 sensors’s showed bad so I replaced both and in a static test IE holding rev’s up at about 3000 with the car stationary it seemed to be good but when I took it for a drive it was still the same.

If the engine is under load as in accelerating or going uphill it seems fine or for the first few minutes when it is cold it seems OK but as soon as it warms up it starts cutting in and out.

Any ideas?

[bohuler]

Exhuast blockage? Undo the flange below the headers and repeat test. If no change move to the flange behind the cat and try again.

Dave

[tonyevans]

I am not doubting you at all Bohuler but it runs fine otherwise - How would that cause this problem only? Just trying to learn.

How do I drive it up the road with the exhaust hanging?

[bohuler]

No need to have it hanging, just undo it enough to separate the 2 flanges.

It sounds like the way my GV was running with a munted catalytic converter. It 'fixed' itself when I went to chop out the exhust with a sabre saw and only got half way through.

Before the chop it would idle fine but under load it would break down and not get above 2500-3000rpm. It was like it was hitting the rev limiter is the best way to describe it.

Dave

[tonyevans]

AH! OK - No mine is revving out fine and will pull fine it is only when the revs/speed levels out and the motor is just trying to maintain speed with no real load.

[tonyevans]

Right - I have replaced BOTH O2 sensors and the Throttle Position Sensor but no change so have done a Video so you can hear what it is doing.

It starts fine, fist time every time hot or cold.
It has a very slight pulse in the revs at idle.
When I raise the revs to over 2000 (Anywhere over) and hold it steady it cuts in and out as you can hear in this video.

https://www.youtube.com/watch?v=CZhm7qi ... e=youtu.be

Sorry don't know how to embed a video

Any ideas what I can try next?

[zoukshin]

Wow that's weird ... gas pedal cable steady, but the revs go a bit nuts. That screams sensor issue or ECU to me.

[fordem]

I know you've changed the TPS already, but, that's what I think it is - try connecting a volt meter to the center pin and with just the ignition on, measure the voltage as you slowly open & close the throttle, is it a smooth variation? You can also use the Rhinoview interface & software to see what the ECU is seeing for throttle position.

What I'm thinking is that the fuel is being cut which happens if the ECU thinks the throttle is closed (from the TPS) whilst the engine rpms are above idle - for example, if the engine is on the over run, because you've down shifted on the approach to a corner - it will disable the fuel injection, until the rpms drop (I don't remember the exact rpm) and then enable it, probably at a level based on airflow from the AFM, rpms will then jump and the cycle repeats.

[tonyevans]

Thanks Fordem. I will try getting Rhinoview working today (I have been having problems with it disconnecting on my new laptop) What you say makes sense and that is why I replaced the TPS.

[tonyevans]

It has been suggested by a local mechanic that it is the Mass Air Flow but after emailing Greg at 4WD Products he says there is no listing for the sensor only the whole throttle body? Can anyone shed any light on this?????

[fordem]

No, Suzuki does not supply the MAF separately from the throttle body, it can be removed, I believe there are third party sensors available, and I'm fairly certain I've seen people complain that they don't work properly.

[tonyevans]

OK - I have a MAF sensor just arrived from the USA but will not have time till next week to fit it.

I can see why Suzuki say don't touch it inside or try to clear it. Fragile is the word all right.

If anyone is interested I will try and get a picture of the inside the intake bit.

[MacDaddy]

tonyevans wrote:

OK - I have a MAF sensor just arrived from the USA but will not have time till next week to fit it.

I can see why Suzuki say don't touch it inside or try to clear it. Fragile is the word all right.

If anyone is interested I will try and get a picture of the inside the intake bit.

Yes please...

[tonyevans]

MAF For V6 2.5lt GV



Inside the tip

[tonyevans]

I finally got all the other "Must Do" jobs done and have had time to get back to this one.

I put the new MAF sensor in but it is still the same and I still can not get Rhinoview to connect and stay connected to the ECM so I guess it must be the ECM little black box that is at fault. Anyone know the best place to look for a working one?

[atari4x4]

that's really odd tony, maybe remove & pop the top off the ecu to see if there are any blown resistors etc. they do suffer from getting wet when the a/c drain blocks, wonder if it's water damaged at all?

to embed youtube vids, hit the share button on the youtube vid, copy the jibber jabber that looks like this "http://youtu.be/CZhm7qinyYs"

delete everything that's not in bold http://youtu.be/CZhm7qinyYs

bung the youtube tags on it [youtubehd ]CZhm7qinyYs[/youtubehd ] so it looks like this without the spaces.

and bam, there is your vid, wonder if it is an ecu problem if you can't get rhinoview to work?

[tonyevans]

Finally got back to this and decided that even though the ECU was NOT putting out a error code I would pull it out and open it up and think I found the problem - I find it hard to understand how it worked at all?

[atari4x4]

that's crusty... check the a/c drain, it's probably blocked.

[JrZook]

Looks like a pretty high tide! It is an engineering marvel when the ECU is positioned under a heater core or a vent. Demands highest spare parts profit.

With a can of contact cleaner and a scrub you *might* be able to save it depending on the underlying damage.

[zoukshin]

Wow I can't believe it still worked. The code must not do much (if any) CRC - there is no way all this crap wouldn't change the capacity, resistance, inductance etc. between circuits.
Also, is that PoS not sealed at all ?
I am absolutely shocked ... that can happen to all of us GV owners. Any good tech to minimize the risk ?

[tonyevans]

As Atari said it's the AC that gets it - I have found a replacement and it WILL be waterproofed before installing.

[murcod]

Wow, I'm amazed you were able to even start the engine!

You might be able to salvage that ECU. Isopropyl Alcohol is what is used in the electronics industry to clean PCB's (printed circuit boards) off - use it with a short bristled brush to remove all the crud. Then it let dry completely. You never know, once it's clean (removing all sorts of odd resistance problems) it might be okay.

[ninjamoses]

Far out, kind of impressive that it even worked at all. You've got me curious now - think I'm going to rip mine out and take a peek also just to make sure.

[tonyevans]

New/second-hand ECU arrived from a good (Thank you very much Freefall) so I just plugged it in and sat it on the floor - hit the key and it purrs like a cat - Rang the blue slip tester in the Ridge and he is off on holiday so another week or so before Rego

[tonyevans]

Hey Atari - Where is the AC drain please - My FSM says Nothing about it?

[fordem]

At the bottom of the evaporator housing - exits low down on the passenger side firewall - look for a couple of inches of 1/2" hose sticking out & going nowhere - usually easier to see from underneath.

[tonyevans]

Thanks mate - I will have a look this arvo ............... Maybe