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VR Calais idle problems

Poor old Dad

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Hi all,
new to forum. Well set out and very helpful people. Thanks for the opportunity to seek help.

My daughter's '94 VR Calais conked out on her way to work last Friday. There were no symptoms leading up to it, it just died. She tried starting it but although it fired, it wouldn't idle. It's exactly as if it's run out of fuel. Tilt tray home where she got RACQ to have a look. According to RACQ guy the vacuum was ok but he couldn't pull any codes as he couldn't get a connection between scanner and ecu(??).

So, dad gets to play with it :(

On reading this forum I've cleaned throttle body and IAC (managed to break gasket so a new one made... and then broke one of the IAC screws. Drilled and tapped a new thread, so all good again.)
It idled better after that but still dies particularly if any accelerator is used. (It will rev and hold revs, eg 2000rpm, if accelerator is "feathered" to get it past flat spot, but will eventually die if throttle is released.

Further reading and I used the paper clip trick for self-diagnosis.
At first, code "12". Then code "13"
I reset ecu and then code "12" only.

During one of it's better idling performances (30 seconds) I thought I'd put it in gear but when I put my foot on the brake (to save running into the garage door) it immediately cut out. Tried it a couple more times and same thing - immediate drop in rpm with brake application. More reading in here and then tried expelling brake booster before starting and seeing if pedal got firmer after starting. It did, so maybe no joy there?

I tried fault codes again and after a "12" I got a "13" and then 4 continuous blinks as in "4" - definitely no pause after the first blink (to denote a ten). From then it would not reproduce the "12" then "13"... it just kept blinking 4 times.

So, where it's at now is a very erratic idle. If it will idle, it sounds like a very lumpy cam. It varies anywhere between 500 and 1000 rpm. A huge flat spot if accelerator used. There's no check engine light on.

I'm lost so would appreciate any help you guys can share.... cheers.

edit: just removed throttle body again and checked IAC operation. It seems to work ok... about 2mm movement??
 
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FstStig

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Daughters phone number if she is over 18 and I'll give you the answer LOL :p

Seriously though

Sounds like its either your Coil Packs and DFI Module, get yourself a Multimeter and test these, make sure they come to the factory specs. You may need to get yourself a Gregories or a Haynes workshop Manual. Try giving your MAF (Mass air flow sensor) a clean its the sensor after the Air box. Test this with your multimeter as well. Check the Spark plugs gap and also the resistance on the Spark Plug leads..... If all of the above check out ok, move onto your Injectors as it sounds like your missing on a cylinder or 2.
 

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Edit: Just notice it was a VR so no MAF, you will instead have a MAP sensor (Manifold Absolute Pressure sensor). This will be located at the back on the fire wall on the Passenger side.
 

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Edit 2: code 13 = O2 Sensor or Oxygen sensor. These are a sensor that go into your exhaust, not that hard to replace and is most likely your problem :)
 

Poor old Dad

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Thanks for taking the time to reply, Mumboman.

I was thinking about oxygen sensors but am a bit concerned about throwing money at it when the codes are inconsistent or at least it seems that way to me.

I'll get the 02 sensors tomorrow and let you know how it goes.

(if you're a Commodore mechanic I'll send my daughter's phone number along, I'm getting too old to be crawling around cars, lol)
 

Brett_jjj

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If the engine is stalling or changing revs when the brake pedal is pressed,then it sounds like theres a vacuum leak somewhere,Id first try disconnecting the brake booster vacuum line from the booster,then block it off with your thumb and run the engine,keep it blocked and see how it runs then,if it runs fine,the brake booster diaphram is probably faulty.If theres no change,then reconnect the booster vacuum hose and check around the rest of the engine's vacuum lines for splits, cracks ,disconnected hoses etc.Pay particular attention to the rubber hoses and lines that go to/from the plenum on the top of the engine.Theres also a vacuum reserve line under the left front guard.It looks like a black plastic ball,this has a vacuum hose going to it,so check that as well.Id also try another IAC valve if nothing else works.Ive seen one cause problems before with idle etc,and it didnt even set off an error code...
 

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I suggest you give everything a good clean first and do the vacuum leak test as Brett_jjj has suggested, these are cheap and generally free and easy to do. If you do all of that and the problem is still there, then I would suggest moving on to the O2 Sensors as this is the code it is spitting out. Each code will repeat its self 3 times over before moving onto the next code. So did it throw out a code 40?
 

Poor old Dad

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If the engine is stalling or changing revs when the brake pedal is pressed,then it sounds like theres a vacuum leak somewhere,Id first try disconnecting the brake booster vacuum line from the booster,then block it off with your thumb and run the engine,keep it blocked and see how it runs then,if it runs fine,the brake booster diaphram is probably faulty.If theres no change,then reconnect the booster vacuum hose and check around the rest of the engine's vacuum lines for splits, cracks ,disconnected hoses etc.Pay particular attention to the rubber hoses and lines that go to/from the plenum on the top of the engine.Theres also a vacuum reserve line under the left front guard.It looks like a black plastic ball,this has a vacuum hose going to it,so check that as well.Id also try another IAC valve if nothing else works.Ive seen one cause problems before with idle etc,and it didnt even set off an error code...
Thanks for that Brett. I checked vacuum lines as best I could and couldn't find anything suspect. I thought about getting anotehr IAC but again wasn't sure about it and didn't want to spend $500 on different bits and pieces when I don't know what is what and how it's 'sposed to work. I actually did crimp the booster vacuum line with a pair of pliers. It didn't make any difference to the idle (which I thought meant it is ok?) So, if the booster diaphragm is faulty does it effect idle at all times or only when brake is applied?

I suggest you give everything a good clean first and do the vacuum leak test as Brett_jjj has suggested, these are cheap and generally free and easy to do. If you do all of that and the problem is still there, then I would suggest moving on to the O2 Sensors as this is the code it is spitting out. Each code will repeat its self 3 times over before moving onto the next code. So did it throw out a code 40?
Thanks again Mumbo... yep will follow your advice. Maybe a trip to the wreckers and pick up a few second hand bits and replace one by one until problem solved.

Probably it was a code 40. Didn't think of 4 x 10 - was thinking of 4 x 1. I'll look up code 40 and see what else in in store... cheers

edit: can't find a code 40 - there's also no code 30 or 50 either - or am I the only one who doesn't know where to look for those? :)
 

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Id just get a second hand IAC valve for a few dollars,see what happens then,also usually when the booster is faulty it will either leak all the time or make a hissing sound.I cant remember if the it makes a difference if it does it when the brake is pressed or not,its been a while since ive seen one,but you can test the booster,just try the following,with the engine off,push the brake pedal a few times to deplete any reserved vacuum.Then hold the pedal in firmly and start the engine,if the pedal sinks in as the engine starts,then the booster is ok..
 
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