Austin09

Hi everyone. I have a problem with my turbo system and hoping someone knows what it could be.

I've spent a few hours reading up on the turbo issues on a few forums and clarks garage but noones symptoms have been exactly the same.

I just got my car back from the bodyshop where it had a front end and sill respray (bonnet off). They had it for 3 weeks so maybe the battery is an issue? He said it didn't go flat at all as he moved it around the workshop a couple of times.

Since I picked it up I've only got just over the 1 bar of boost. No noticeable increased power from the turbo at higher revs. You can hear the turbo spool up as revs increase, there are no weird noise, this sounds to me the same as it did when it was working.

When driving along, the reading goes up to 1 bar as per normal, then when you get to the 3-4k mark when you expect it to boost, it only goes up a little to maybe 1.1 / 1.2.

According to the forums, after checking the hoses (which I've done) I should take off the hose to the wastegate and drive to limit my diagnosis to the rest of the system.
The only thing visibly damaged on the hoses is the brake servo hose which has melted a bit from contact with the bonnet. I've put some RTV on that for now until my replacement comes.

Any help is appreciated. I've got all weekend planned to work on it and desperately want to get this back to full power.

Austin09

Update. Disconnected the cycling valve plug and took for a test drive. No difference to drive or gauge. See youtube clip of test drive. Foot to the floor when on boost.
When slowly accelerating, the boost climbs a little then slowly drops off.

Dougs951S

Disconnecting the CV plug is not an appropriate trouble shooting method, you need to clamp off the line to the waste gate and then drive it to see if it makes pressure. If it still wont boost, I'd pull the boot off the turbo intake to make sure the compressor isn't toast. I said those exact words last week to someone else with the same issue. For them, it ended up being the turbo was junk... Your wastegate could also be toast in that situation but you would know that, you would hear all kinds of crazy spooling sounds as the turbo fought the giant boost leak.

divil

Is the throttle position sensor definitely plugged in? An unplugged TPS will definitely cause that exact behavior. Maybe a faulty one could too...not sure about that.

Austin09

I was expecting this would be electrical given that it was fine before the body shop had it. Bonnet and badge panel was removed for resoray.

I will clamp hose to WG as per suggestion and report back. Also will try reconnecting TPS.
Is there any way of testing these sensors work, perhaps with a multimeter?

fejjj

I had the same issue and it turned out the cat was clogged.

Austin09

Another day of troubleshooting:
Clamped off CV to WG pipe - no difference.
Tried disconnecting battery for a while and reconnecting - nothing.
I can hear the TPS click when the throttle is moved - so relay is clicking at least.
Will blink test tuesday.
I've just bought a hand suction pump online so I can test the pipes and WG tuesday.

I'd like to rule out the exhaust system (although its blowing in a few places) since the car was fine 3 weeks ago, hasn't been driven, and has stopped working when I picked it up.
I'm thinking electrical, or a nicked hose during the badge panel / bonnet removal and reassembly.

If I was to get a new WG where should I go to get the best priced stock one?

NM'87 951

If it was working before the paint job and now isn't I would be looking at vacuum hoses that may have been pulled loose or disconnected. I might also look to be sure banjo bolts and other clips are tightened. I would find it unlikely that the car suffered tragic damage while being moved around a paint shop, unless someone isn't telling you something (may be someone joy riding?).

When I re-did my vac lines I had some similar boost issues and after going around and shoring things up I was able to get back to baseline.

edit: stock parts can be had cheapest from members on forums who have replaced them with modifications. kits to rebuild stock parts are also available if your wrench hand is strong.

mel_t_vin

Three weeks, and the hood was removed.

Clogged cat/downpipe is a possibility, as either the exhaust is being restricted or the intake is bleeding boost.

When I encounter an issue, I tend to look for the simple things. Look for hoses, downstream of the turbo, that would have easy access [to damaging objects] with an open hood. I'd start with the two intercooler hoses. Then, check the hose at the compressor outlet and the hose at the throttle body.

Guess you could always pressure/smoke test the intake tract.

On a separate note, this [1.2 bar] sounds suspiciously like limp home mode...check the CV connection and make sure it tests within spec.

Austin09

Thank you guys this is really helping guide my time with the car.
I've checked the hoses visually, a couple are a little loose, the worse being one that attaches to the underside of the throttle body.

I'll test this with a vacuum pump tonight - what sort of pressure should I be running through, and am I looking for it to hold for a certain amount of time?

I've done the CV test by clamping the pipe to the WG. I'll vacuum test the hose to the WG tonight and also check to see if the cross over pipe (is that right?) gets hot as it may be stuck open.

I also have made my own blink test so I'll be checking fault codes tonight.

I've checked fuses. Could it be anything else simple like that? The battery feels more sluggish now so perhaps it was almost flat and has affected the computer or solenoid? (i'm guessing now)

mel_t_vin

What does a little loose mean? A couple turns of the screw driver?

The in-dash boost gauge receives its electrical signal from the KLR, which reads boost pressure from the intake manifold. If the gauge is only reading 1.2 bar, then you either have a) a serious exhaust restriction, b) a serious boost leak, or c) a compromised [failing] turbo charger.

Re: b), hoses that "are a little loose" are probably not your root cause. When you visually check the hoses/connections between the compressor outlet and the intake manifold, you need to squeeze the hoses, looking for punctures/slits that blow open under boost, venting pressure, and close back to [nearly] normal under vacuum.

Re: c), while you're performing b), above, at the compressor outlet hose, remove the j-boot and examine the condition of the compressor wheel, looking for excessive play in the shaft or FOD to the wheel itself.

Re: a), short of an actual [painstaking] visual inspection, I suspect welding in sensors to read pressure drop across the downpipe/cat would be the only other option.

Keep us posted.

Austin09

I tested the car a little tonight.
I want to determine whether it's the CV or the WG or the hose between first.
I can't blink test until tomorrow so I started by disconnecting the hose from the CV and seeing if
1/ it held vacuum
2/ if the x over pipe got hot before th vacuum and after

Results
The x over pipe was hot before vacuum testing so makes me wonder if the WG is stuck open

The vacuum test is shown in this video
http://youtu.be/nb0c0VLwGdc

Any suggestions where I go next?

NM'87 951

Seriously just sounds like a small vacuum leak. Go over all your lines and make sure everything is fully seated and all clamps are tightened. You can take off your Jboot (leading into the turbo intake) and check the fan blades and see how it spins and check for any breaks or chips. If you had any serious issues you would know it. You said there were no weird noises and haven't reported any other connected issues.

If they had to take off the bumper and/or hood they may have needed to move lines in those areas including the intercooling piping and vac lines from the intercooler lines to the CV under the intake manifold. This is why I think to check all the connections and make sure your routing is all correct. Lindsey Racing have good vacuum system diagrams on the website with their vacuum line kits.

NM'87 951

There are threads on here about the difference in turbo response between WOT and roll in throttle. Perhaps checking those out and looking for answers might help you some.

Austin09

I've carried out a visual inspection of all the hoses and connectors, other than the connection to the WG. They seem fine but the small vacuum hose connection to the underside of the throttle body can be pulled off with ease.

Should the hoses all hold vaccum? I'm unsure which ones I'm testing with the pump should hold vacuum. The one in the video I assume should?

Give the boost stops at 1.2, I'm assuming this is electrical. No strange sounds at all and it spools up fine to the 1 bar, then the boost is limited (see test drive).

I am concerned the x over pipe got hot straight away, so the WG may be stuck open?
I can rule out electrical faults tonight after I make the blink tester.