Is my engine mending itself ?

[K9d 108]

You can admire my handy work tomorrow.

[K9d 108]

Now that my car has 4 new tyres and Smaky has sorted my sticky rear caliper and changed my knackered upper wishbone its loads better, but the overboost issue is beginning to real annoying me.

Tomorrow, with Kathy's help, I'm going to check the actuator rod is moving on engine start up, I'm hoping it isn't then I can try and free it.

I will also do a throttle reset, because as Alex pointed out, it works like an ON/OFF switch, hopefully this will give a more linear throttle response.

[LJ_GQV 115]

good luck

[K9d 108]

Had a look yesterday, the actuator moves about 4mm when the engine starts, or when I disconnect and reconnect the vacuum pipe if I get in there with a screwdriver I can move some more and it will stay there until I disconnect the pipe.

 

I have sprayed it up and moved it several times but it still doesn't do the full movement.

 

I cut a piece of pipe off, so I could take it to a shop and get some new pipe, I handed the bit of pipe to Kathy as I reconnected the remaining pipe. We walked back to the house, Kathy in front, as we got to the front door Kathy lifted the lid on the wheely bin and threw something in "what did you throw in there", "that bit of pipe" , so I then had to empty the bin to get it back out.

 

The car seemed a bit better but I could still get the overboost issue if I tried.

 

I now have some new pipe and will replace it today and see if that helps.

[Smaky 73]

It's still the split boost hoses that are the main concern here.

[K9d 108]

I agree, but my budget doesn't allow me to address them right now. , when I can I will replace both with silicone hoses.

 

I did a throttle reset yesterday and changed the vacuum hoses, its hard to put a finger on but it just feels better, smoother and quieter, so progress is being made.

 

Insurance due next month so that will mess the budget for a while.

[Devious 4]

The overboost / surcharger Value codes are a baffling one.

I replaced map, maf and long shot crank sensor, cleared all the codes, fettled with the actuator and checked over EVERY pipe with fairy liquid and a short length of hose to pinpoint any hissing. NOTHING. Still have the pesky EML when I hit 3.5/4.0k revs and limp mode for 5 seconds.

Have you developed the "policecar in the distance" whistle from the turbo yet?

Ta

[K9d 108]

That's exactly how it is, can make overtaking interesting.

The "police car in the distance" has been there ever since I bought the car 18 months ago, never got any worse, most noticeable when the sound can bounce off walls.

[K9d 108]

Time for an update.

 

My hoses are still the originals, but I have repaired the top hose with some of this http://www.ebay.co.u...=item564d214ac4, but black not clear, it seems to have done a brilliant job no more oil leaking and no pressure being lost. In fairness to the Halfords tape I hadn't applied it properly, there was a backing layer I hadn't removed.

 

I still need to get a bottom hose, I don't think its leaking but does appear to be made of tape and is very easy to squash, so a trip to EB Spares next week.

 

I sprayed the VNT rod and moved it as best I could by hand at the weekend.

 

Now when I drive it the EML light will come on at 3-4K, generally moving up the rev range after each incident on a journey, the car is much quicker now and feels a lot more lively. When the EML comes on it does seem to restore power much quicker, it used to be a case of rev it hard in 3rd then do a slow shift to 5th allowing the revs to drop to tickover and the power would return. Now I can usually get away with a normal shift from 3rd to 4th and the power will return and if not going straight up to 5th and its back again.

Also the throttle is more linear now, before it was like a switch with pretty much all the power coming in at very light throttle, now its spread across the whole movement.

 

Apart from the bottom hose I'm thinking along the lines of weak vacuum, weak VNT rod actuator or dirty MAP sensor.

From pictures I have found am I right in thinking the MAP sensor is at the back of the engine, between cylinder 3 and the bulkhead ?

How can I test the vacuum and the actuator ?

[Smaky 73]

Yes, the MAP sensor is on the inlet manifold.

[K9d 108]

Another update, my engine has started to leak boost from somewhere, I can hear it above 2.5k rpm, its not the top hose as my repair is still clean, no oily muck coming out

As an experiment today I disconnected the vacuum hose to the (N75) VNT solenoid and plugged it with a bolt and went for a drive.

My understanding is that with no vacuum the VNT will be in the high rev position and I should lose boost at lower revs.

On driving there was more turbo lag at low revs, but it still drove fine, I guess being a 2.4 helped, once the boost was there it stayed there and I could still travel at 30mph in 4th about 1,250rpm.

When I got on an open road I floored it in 3rd, there was more lag than normal and less power under 2k, but once the power came in it went very well and no EML plus there was almost no noise from the leak.

This would suggest less boost pressure.

I'm now wondering if my N75 is knackered, is it possible that sense enough vacuum to pull the VNT halfway and then stays there no matter what the engine is doing.

I was hoping to get to Swindon tonight but family commitments got in the way

[K9d 108]

I've decided to try and get to the bottom of this problem, dodgy turbo hoses aside.

Bought a vacuum pump and attached it to the VNT actuator, it starts to move at about 300 mm Hg, pauses in the middle where it normally sticks and then jumps to full movement at 700 mm Hg. I've given everything a good spray in there and it got smoother, still a little pause in the middle position before moving to full.

I tested the vacuum before the N75 solenoid and that was giving 700 mm Hg, so it seems the car is supplying enough vacuum.

 

Unfortunately I can't test output of the N75 because I broke off the output connector trying to get the pipe off.

 

I am beginning to think the N75, is the issue here because the overboost issue was none existent with it disconnected, my thought is that its stuck in one position and doesn't allow enough vacuum through for full movement and doesn't release it at high RPM.

 

As a temporary fix I've bypassed the N75 and the actuator is going straight to full movement and staying there, even with the engine off which would indicate that the diaphragm is fine.

 

Next thing is to order a new N75 and see what happens when its fitted.

[Smaky 73]

Supplying a vacumm?

 

This will need the VNT seting up.

[K9d 108]

Is that something that needs doing when I replace the solenoid ?

[Smaky 73]

nope, it's because there is a problem with the turbo, which is why the VNT is sticking

[K9d 108]

I thought it was a problem with the solenoid because the VNT moves properly, full movement, when I bypass the solenoid or use my vacuum pump to test it.

I have to replace the solenoid anyway.

Because the car has 185,000 miles and is 12 years old and producing blue smoke on start up I'm reluctant to spend too much money on it.

What is a ballpark figure for sorting the turbo ?

[Smaky 73]

All depends on whether the shaft is corroded or not, as it is normally that which causes the VNTs to stick, though I'm also hoping it's not an impellor bearing fault as that would spell disaster in the long term, basically the vacumm pressure is correct and the solenoid is new and working so the issue has to be on the turbo unit itself, I can't speculate on cost due t the unknown codition of the turbo but as it seems to have full movement available I don't think it would hit too much (would probably be more in diesel getting to me).

[K9d 108]

I think we have crossed wires here, the solenoid is not new yet, I broke the old one yesterday and the new one is ordered but not yet arrived and fitted.

When it does arrive I will fit it and see what results I get, I will test it before and after the solenoid with my vacuum gauge to see if whats going in is also coming out when it should.

[Smaky 73]

Ah, OK.

[K9d 108]

Update.

 

New solenoid arrived today, so I decided to be scientific and see what difference it made to the vacuum.

 

Before solenoid 700 mm Hg.

After

Old = 375 mm Hg

New = 475 mm Hg, I was disappointed by how little it had changed.

 

VNT movement

Old about 1/2 movement

New about 1/2 movement. even more disappointed.

 

I then revved the engine whilst watching the Vacuum gauge and the vacuum reduced as the revs rose, I didn't do the same test with the old one.

 

I then removed my gauge and connected everything as it should be, still about 1/2 movement on the VNT rod.

 

Went for a drive, straight away it felt better low down, but I did think it may have been a placebo effect.

I decided to do a control test and left a 30 mph limit in 4th and accelerated, the same as I do every day on the way to work, there was definitely less lag and a better response.

Next test was full acceleration in 3rd from 1,500 rpm, good to start with but then the EML light came on at 3,500 rpm , so now I'm thinking that's £57 wasted.

On to my private test track for a decent run, start in 2nd and up to 4.5 rpm in each gear, 2nd good (but it always is), 3rd good (normally EML at this point), 4th good, but I couldn't reach full revs due to an obstacle.

I did 4 runs in total, hitting 3 figure speeds and high revs in all gears except 5th, no EML no loss of power, no nasty shocks just a small noise of air escaping my dodgy turbo hose(s).

I did another test of full throttle in 5th from 40 mph to 100 mph, good smooth acceleration, no EML.

When I got home I popped the bonnet to check the VNT rod it was on full movement as it should be, I unplugged the solenoid and the rod returned to its neutral position, then I reconnected the solenoid the VNT rod went straight to full movement with only a tiny pause in the middle.

 

So now I'm a happy bunny.

 

Next on my list is new turbo hoses, sort out the brakes and change the noisy aux belt pulley.

[Smaky 73]

Hoses can be got for cost price from my supplier.

[K9d 108]

I'm having trouble tracking them down so if you can PM or text me the price I will get them through you.

Its the 140 bhp version, as far as I know.

[Smaky 73]

Will call tomorrow

[K9d 108]

Cheers

 

Car is so much better, did have one incident of the EML, that was on an uphill stretch of dual carriageway where it has always been a big problem, apart from that though lots of lovely smooth and instant response.

[K9d 108]

Another update.

 

I fitted new hoses on Tuesday, my temporary repair had failed so they were leaking loads, especially the top hose.

 

The bottom hose seemed to be what was left of the old hose and lots of cloth tape, not my handy work but apart from being very squashy appeared to be a good job.

 

Both hoses were replaced and after a few days of driving the engine is much better, throttle response is almost instant, it pulls much better from low down and feel like there is more torque in the mid-range, plus it has got its deep growl back.

 

One the down side I am getting the occasional EML again, mostly in 3rd and at full throttle, but it seems to clear quicker and with the extra mid-range is easier to drive around.

 

I'm not going to chase it anymore, the engine is much better than it was before the new solenoid and hoses so will stick with it as it is.

 

I think my brakes are the next thing to look at they tend to fade too quickly, but will have to wait as I need new front tyres and tax is due at the end of April.