Pulling my hair out - idle probs & lack of power

Paul240480 · Post by **Paul240480** » Sat Aug 23, 2008 7:36 pm

1991 Turbo Auto with 144k miles.

For about the last 15k miles, every 2-3k a lack of power and majorly erratic idle occurs. Revs going from 3-20k over & over. Normally I find the plugs blackened/sooty & a quick clean up sorts it.

To fix, so far I've carried out the following:
Cleaned the Idle-Valve (brill 'how-to' on here).
Replaced perished pipes on Turbo intake.
Replaced perished braided hose under throttle body.
Replaced air filter
Replaced HT leads
Changed plugs (Tried Champion, tried BERU - now on NGK).
Air Mass Metre is only 5 yrs old & I've tried altering resistance.
Speed sensor has also been replaced & resistance is spot on at 220 Ohms

Not checked yet, but I reckon I'm gonna find the plugs sooty & black AGAIN when I look.

I'm now stuck as to what to try next. Thinkin' about chucking it in to a garage (wallets trembling) Got MOT on 29/08 so will probably wait the result of that before spending.

So have any of you kind soles got any suggestions please?

Thanks

Iroll480 · Post by **Iroll480** » Sun Aug 24, 2008 9:59 am

I think you should check the Lambda and it's connections. In the Howto part there's an excellent article from Johnturbo on how to test it.

Paul240480 · Post by **Paul240480** » Sun Aug 24, 2008 1:16 pm

Thanks Iroll480.

Had a peek at JTs brill 'Howto'. Bin' waiting for the rain to stop and have only managed to get one plug out before rain started again. The plug was as sooty as a sooty thing, as suspected.

Will carry out a Lambda test soonest.

Paul240480 · Post by **Paul240480** » Sun Aug 24, 2008 1:59 pm

Okay, I've managed to dodge the showers & have got as far as removing the battery & tray in order to access the wires to test the Lambda Sensor.

However I can't see the wires

This is what is there:

Can anyone point me in the right direction please.

480_rocket · Post by **480_rocket** » Sun Aug 24, 2008 2:51 pm

Have a look under the cold air feed to the air filter box. If you still can;t find them, trace them back from the Lambda sensor on the cat. On mine they ran along the subframe then up to the battery tray. At that point there were the connectors.

Paul240480 · Post by **Paul240480** » Mon Aug 25, 2008 9:13 am

Right I reckons I've found the connector. On mine there are three wires coming from the the Lambda. Two white & one black. At about 18" from the sensor are connectors. Two wires, the whites go into one & the other goes through a 'bullet' connector and comes out green/yellow (Earth I guess). They then all go into a gret sheath and carry on to join other wires in a bigger sheath up near the battery area.

So that explains why I could'nt find the connections under the battery
tray

Will try to test it from under the car now - another stiff neck comin
on

BTW these guys seem to do a copy Lambda:

The universal equivalent to the Bosch direct fit 0258003060 is LS02
http://www.lambdasensor.com/main/muniversal.htm

Anyone know or used these guys?

Cheers.

Paul240480 · Post by **Paul240480** » Mon Aug 25, 2008 10:08 am

I think me Lambda is okay. Carried out the test as per JT's instructions.

After 5 mins of idling I read the metre which gave a steady 0.607 voltage.

JT's how-to say if you have a steady 0.8 that equates to possible incorrectly set MAF. I guess mine is close enough to be just that so off to test that next.

Oh, best search on here first to make sure I get it right

Paul240480 · Post by **Paul240480** » Mon Aug 25, 2008 11:15 am

I've now adjusted the resistance of the MAF Sensor & after each adjustment have re-checked voltage at the Lambda.

Can't seem to get a fluctuating reading at all. These are the readings:

MAF Resistance Lambda Voltage

382 0.6 (Steady)
480

0.55 (Steady)
600 0.53 (Steady)
900 0.57 (Steady)

Then tried to go higher but it would not go above 930 Ohms. So put it back to: 900 0.53 (steady)

I've left it ticking over for about 10 mins now &...........

It sits at 0.59 for about 7 seconds then drops to 0.6 then 0.4 then back to 0.59 for about 7 seconds and so on?

For good measure I tested resistance on the Timing/ speed sensor at it is 273 ohms so within the acceptable.

The good news is that it seems to be ticking over smoothly now, so I've left the MAF at 900. Not sure if this is the right thing to do or not, but thought as Controle Technique (MOT) is due on 29/08 I'll leave & stick it through before spending anything!!

I do hope my ramblings are not boring you all too much

JohnTurbo · Post by **JohnTurbo** » Mon Aug 25, 2008 2:03 pm

Paul....sorry its taken a while for me to get to this.

The 480T is a bit bamboozling when it comes to the lambda sensor...

Every other car i've owned fluctuates from 0-0.2 to 0.8 volts and back and makes a nice square trace.

However:- If you can get yours to be fluctuating a little around the 0.55 volt area its very likely its fine, but for your piece of mind an additional test:-

With the engine running and warm, get somebody to blip the throttle (for around a second or two, say 4500rpm). As the engine recovers down to idle speed the sensor should see a FULL RICH reading of close to 0.8v.

Check also that with the ignition on (in the running position) but WITHOUT the engine running, the sensor reads LEAN....0-0.3v. Make sure the engines been stopped a while...so you might wanna do this test first! Really the ignition should be on (not engine running) for 30 secs to allow the tip of the sensor to get hot from its internal heater prior to this test.

Paul240480 · Post by **Paul240480** » Mon Aug 25, 2008 5:04 pm

Thanks JT

Will give that a go.

(Took it for a spin earlier & all was fine. On Sat it very nearly failed to get me home, coughing & spluttering etc etc. Got overtaken by a 2CV of all things

)

JohnTurbo · Post by **JohnTurbo** » Mon Aug 25, 2008 6:49 pm

Not as bad as me getting owned by a fiat ducato van in my skyline when it was poorly

Paul240480 · Post by **Paul240480** » Fri Aug 29, 2008 11:40 am

Woohoo, we passed first time! A few advisories though

See here: http://volvo480.dragons.org.uk/forum/vi ... hp?t=16746

As I've posted a question about wheel-bearings

Paul240480 · Post by **Paul240480** » Fri Oct 10, 2008 11:32 am

Okay. So we've had a couple of weeks of the 480t running superbly. SWMBO came home today to say that the idle is starting to be a bit up & down, but car is performing okay.

Checked me plugs & yep, just starting to choke up again (SWMBO's getting good at detecting this now

).

So I've brushed the plugs off again & its fine - for a few weeks no doubt

So, JT I've checked as you suggested & general opinion is that the Lamda's okay.

So having done all as listed at the begining of this thread, my only other thought is to if the fuel mixture is too rich? (obviously any other ideas would be welcome). Is there a way of resetting the mixture without going to a garage?

Fuel consumption is about 26.2 which I think is low (yes it is turbo & auto) as when I bought the car in 2002 we averaged around 29. The car had 100k on purchase, now has 145k.

Cheers.

BTW, just for interest, I post also on a French Volvo Forum (only general posts, not tekky ones as me French is not up to tekky stuff

). But have learned that a 480 T Auto is a rare beast over here. They got turbos but rarely with auto-box

)

JohnTurbo · Post by **JohnTurbo** » Fri Oct 10, 2008 12:26 pm

I'm thinking air leak....especially under boost. - Causing a rich condition.

Somewhere sly, such that at idle the pressures aren't such to show the issue.

Perishing boost pipe par example!

Paul240480 · Post by **Paul240480** » Fri Oct 10, 2008 1:41 pm

JohnTurbo wrote:I'm thinking air leak....especially under boost. - Causing a rich condition.

Somewhere sly, such that at idle the pressures aren't such to show the issue.

Perishing boost pipe par example!

Thnaks JT. If you mean the boost pipe down at the turbo intake, the one with about 4 'exits' on it, mine was split. I've replaced it with a gooden' from Steve Quinn at 'Volvo Valley'. All of the others appear sound, right upto the MAF sensor & jubilee clips are nice & tight. I've also replaced that little braided hose under the throttle body. Mine was 'shot'.

Are there some pipes elsewhere you can think of, that maybe I've not checked?

Thanks.

JohnTurbo · Post by **JohnTurbo** » Mon Oct 13, 2008 9:07 pm

Any pipe between the MAF sensor, near the battery...right through the turbo, intercooler, and to the inlet manifold, and also the little pipes attached to the manifold.

Paul240480 · Post by **Paul240480** » Tue Oct 14, 2008 2:34 pm

Hi.

Right, first job was to clean up me plugs AGAIN

Then went onto checking those pipes once more. Did'nt find anything glaringly obvious. But after a good half-hour of it ticking over, up & down and all over the place whilst wiggling pipes again & again, it suddenly suddenly settled. Not sure quite what I did, but I was in the area you mentioned JT, between maf & turbo intake (having tried every area you suggested methodically). I have a feeling that it maybe the 'big' pipe from back of the maf which bends down towards the turbo intake before joining another pipe. This shows the begining of perishing. So I've nipped up the jubilees a tad more.

Just been for a good spin, & it's going like a rocket. Turbo pulling like a train, holds third till around 75 ish then moves up & was still pulling approaching 90. Back home tick-over was still smooth.

So, once again we are 'on-test'. If it 'goes' again I'll go straight for that pipe & see if I can defo' give that the blame!

Cheers.

Paul240480 · Post by **Paul240480** » Mon Oct 27, 2008 1:55 pm

Hi. Rough running returned over the last few days

Been out today & once again found me plugs extremely sooty.

Once cleaned I had it running with a perfect idle for nearly an hour. During this time I methodically wiggled, pulled pushed & poked every pipe I could find (all those mentioned in your last post JT). Also whipped the O/S indicator & DRL out & gave all the pipes around the carbon cannister thing the same treatment.

Still cannot find a source of leak & nothing I did made the stable idle alter at all.

Flumaxed

JohnTurbo · Post by **JohnTurbo** » Mon Oct 27, 2008 6:06 pm

Do your plugs have the right heat code?

Paul240480 · Post by **Paul240480** » Wed Oct 29, 2008 7:01 pm

Erm, I think so.

I've tried Champion, Bosch & Beru 4 electrode before. They fouled up just the same.

Now using NGK ZGR5B. Got em' from German & Swedish. Fitted on 24/02 & they've done about 4K miles. HT leads are new.

The dizzy cap & rotor are oem, from GSF too. Do you reckon I'd be better off with Volvo ones?

Volvo 480 Club Europe

Pulling my hair out - idle probs & lack of power

Pulling my hair out - idle probs & lack of power

Confused Now