21 replies to this topic

[fasteddie042]

Hello!

I have a 95 850 5 speed Turbo wagon (HPT) with 240K Kms on it and it has had a limited boost problem since Ive owned it. It boosts to 7-8 psi max and then fades to 4-5 psi. I have replaced a just about everything I can think of :
rotor
plugs
wires
fuel filter
air filter
BCS
and ran through several tanks with injector cleaner.
I was told that it could be a clogged cat that was limiting the boost so I replaced the whole exhaust from the turbo back with an OBX one. I have added a cat and ultra quiet resonator to try to quiet it a bit. In order to accommodate the angled flange downpipe I swapped my 15G with a 16T turbo.
I welded an extra bung in the downpipe so that I can do proper testing of future tunes and when I out the wideband in it was reading very low AFRs (8 - 10) when the boost was low at WOT. The ecu is a stock tune and the only mods are exhaust and turbo (which from what I read is not so much of an upgrade). I pressure tested the inter cooler and piping and everything is perfectly fine.

Today I disconnected the line to the wastegate and the car is incredible, I was careful to not let it boost too high but it now fully boosts with ease.

So I hear that the PCV gets clogged and can cause some problems like this one, is there anyway to test this? Or could it be another issue?

Thanks for any info, I want to get this stage 0.1 working properly before I start with the ECU tunes.

[Bah]

fasteddie042, on 20 November 2009 - 04:54 AM, said:

Hello!

I have a 95 850 5 speed Turbo wagon (HPT) with 240K Kms on it and it has had a limited boost problem since Ive owned it. It boosts to 7-8 psi max and then fades to 4-5 psi. I have replaced a just about everything I can think of :
rotor
plugs
wires
fuel filter
air filter
BCS
and ran through several tanks with injector cleaner.
I was told that it could be a clogged cat that was limiting the boost so I replaced the whole exhaust from the turbo back with an OBX one. I have added a cat and ultra quiet resonator to try to quiet it a bit. In order to accommodate the angled flange downpipe I swapped my 15G with a 16T turbo.
I welded an extra bung in the downpipe so that I can do proper testing of future tunes and when I out the wideband in it was reading very low AFRs (8 - 10) when the boost was low at WOT. The ecu is a stock tune and the only mods are exhaust and turbo (which from what I read is not so much of an upgrade). I pressure tested the inter cooler and piping and everything is perfectly fine.

Today I disconnected the line to the wastegate and the car is incredible, I was careful to not let it boost too high but it now fully boosts with ease.

So I hear that the PCV gets clogged and can cause some problems like this one, is there anyway to test this? Or could it be another issue?

Thanks for any info, I want to get this stage 0.1 working properly before I start with the ECU tunes.

I dunno if its been the same wastegate the whole time, but, theres a thread on here about how the wastegate wont mesh, and thus is always cracked open.

Other way to test this i would say is to get an MBC just to be sure, and set it to whatever PSI

Are you using the stock boostgauge (im thinking not), but, the stock T5 ecu tops out at 9PSI

I dont see how the PCV system could have anything to do with the wastegate opening and closing, so i'd put my money on the wastegate. Either that new BCS just stinks , or, the arm needs adjustment(likely), or its needs the hammer trick (if i can find it ill post back)

Try an MBC to be sure if its the WG or not...Be careful driving with no WG (you know that already)

Also could be the CBV has a rip in it.

[HeavyIron]

Bah, on 20 November 2009 - 05:48 AM, said:

I dunno if its been the same wastegate the whole time, but, theres a thread on here about how the wastegate wont mesh, and thus is always cracked open.

Other way to test this i would say is to get an MBC just to be sure, and set it to whatever PSI

Are you using the stock boostgauge (im thinking not), but, the stock T5 ecu tops out at 9PSI

I dont see how the PCV system could have anything to do with the wastegate opening and closing, so i'd put my money on the wastegate. Either that new BCS just stinks , or, the arm needs adjustment(likely), or its needs the hammer trick (if i can find it ill post back)

Try an MBC to be sure if its the WG or not...Be careful driving with no WG (you know that already)

Also could be the CBV has a rip in it.

may be the wastegate, or vac line issue to the wastegate.

[fasteddie042]

I checked everything on the 16T before it went in, wastegate and cbv. Both actuated the valves fine before I installed the newer turbo and it has only been in the car a couple weeks. I should also add that I replaced all the vacuum lines and both the CBV and wastegate works perfectly fine as well. The wastegate and CBV opened and closed with ease.
The car has had the same problem before and after the turbo swap so I am certain that it is not the turbo.or its associated valves. I did replace the BCS with a used one but it appeared relatively new.

I just read a post on how to test to see if the BCS is faulty but I will have to get some more vacuum line and a splice.


Any other ideas? how often does the wiring to these devices fail?

[T5wagon1717]

I have a similar problems and too have tried lots of thing.
Have you checks your intercooler lines and or intercooler. Thats my next stop.

[StylinMotors]

Did you check your Intercooler hoses? A small hole could be the culprit. It could also be your vacuum lines.

[Dave 54]

When you pressure tested the system at what psi did you do it at, just because it didn't leak at say 5psi dosen't mean it won't leak at 10.

[fasteddie042]

I pressure tested the system at a max of 25Psi and it did hold pressure when I put my finger over the weep hole on the bottom of the intercooler. I am very surprised at how much pressure is lost through that little hole. As for vacuum lines I replaced all of them and all of them seem to hold vacuum. So as far as I can read here it is a big no for the pcv system.

[fasteddie042]

Well! I went to reattach the wastegate vacuum line and low and behold the dipstick popped out of the tube. When I was driving without the wastegate attached I was very careful not to let the car boost any greater than 10 - 12 psi. I am wondering if the car was limiting the boost because the crankcase pressure was reaching its safe limit. Has any one else experienced this?

[Bah]

fasteddie042, on 20 November 2009 - 08:45 PM, said:

Well! I went to reattach the wastegate vacuum line and low and behold the dipstick popped out of the tube. When I was driving without the wastegate attached I was very careful not to let the car boost any greater than 10 - 12 psi. I am wondering if the car was limiting the boost because the crankcase pressure was reaching its safe limit. Has any one else experienced this?

I don't fully understand this.....

The BCS controlls the wastegate, right?

the vacuum hose to the wastegate is connected to the BCS.

The BCS uses a solenoid to limit the pressure going to the wastegate and vents it to the air intake charge pipe if otherwise needed, right?

Theres nothing to even to do with the PCV as far as making the dipstick popping out from that.

If your PCV is clogged that much, then i'd imagine youd have a craptastic idle and the car is running like dog with or without the wastegate.

Is their massive ammounts of smoke coming out of the dipstick? Is the PTC clean? I'm sure the ECU could be affecting the boost since you have the BCS connected up..it could be throwing you into limp mode etc etc..

If the PCV is so bad the dipstick is popping out, then i would change it ASAP regardless of boost issues...

[Cal3thousand]

Sounds like your BCS is not telling the wastegate to close properly and is bleeding boost.

Could be due to incorrect reference pressure at the wastegate or boost pressure reading at the BCS.

[fasteddie042]

The dipstick just popped out today, so it is not a regular occurrence. What I was basically saying was that without the BCS connected to the wastegate actuator the car boosted well past 5 psi. There is no smoke coming out of the dipstick when the car idles. Idling on the car is good and it has never stalled. I have not checked the PTC at all actually, I might give that a check if I can get wram enough to give it a shot over the weekend.

[fasteddie042]

I cleaned the PTC this evening and in the process I noticed that all the hoses for the PCV look relatively new. I am guessing that it was replaced recently. The dipstick popping out seriously concerns me now but with the wastegate reattached to the BCS the dipstick has stayed put. The car still only boosts to 5 psi

[lookforjoe]

fasteddie042, on 21 November 2009 - 03:13 AM, said:

I cleaned the PTC this evening and in the process I noticed that all the hoses for the PCV look relatively new. I am guessing that it was replaced recently. The dipstick popping out seriously concerns me now but with the wastegate reattached to the BCS the dipstick has stayed put. The car still only boosts to 5 psi

Can't say that your assumption is valid. If the hoses are new, the PTC elbow will be very soft & pliable. As it ages, oil cokes inside it. Did you reomve it from the plastic pipe & inspect it? Did you just buy the car? If the dipstick popped, there must be excess crankcase pressure - which could be just because you run w/o the bcs. If so, you're lucky that's all that happened. Do you have a (accurate) boost gauge? How do you know it's "about" 5psi?

[fasteddie042]

I have a pressure gauge hooked up to it, it is not a boost gauge but it is a air pressure gauge used for low pressure pneumatics that reads to 30PSI. That is where i was getting the pressure numbers from. The elbows are nice and soft and the outer surround is nice and soft and it looks to be in good condition. I did remove one elbow and the plastic hose had a little oil but was clear overall.

I have had the car for almost two years and it has never really had much power. I have always wanted to do some basic modifications it but was a bit too busy with school(electrical engineering hey I need some excuse). The best I could do was basic maintenance and I only put about 15K on it during those two years so it only really saw 3 oil changes. This past year I wanted to see if I could start doing some modifications but I have been unsuccessful in even getting it to boost to its stock levels. Frank from Eurosport tuning took it for a short drive and he agreed that it runs smooth but lacks power.

I did a compression check about 4 weeks ago and they were 150 150 155 150 150. So not great but not terrible either.

[Bah]

The dipstick popping out threw me off lol..but we'll go with the PVC system is aight.

The only reason i can think otherwise thatd you be at 5PSI range, and with no BCS your at 12+ PSI easily...is that your running in limp mode.

any CEL light, stored codes, etc etc? Worst case scenario, is you switch over to a new BCS/TCV ( i use the AC Delco, but , my car needs alot of new things so i dont get the full advantage...its by far much more responsive though), if that doesnt work cause its preventing boost from the ECU in limp mode, switch to an MBC

[fasteddie042]

Well the turbo is going to have to wait a bit, forgot to pull the parking brake on the car this morning when I rushed back inside to get something... needless to say there are other repairs that are more pressing...

I will double check the routing of the hoses to the turbo though, any new toys will have to wait unfortunately.

Thanks for the help so far.

[fasteddie042]

I think I finally fixed the boost problem! Since my last set of posts I replaced the TCV with another one and properly tested it. The TCV that I replaced was actualy faulty! Once that was replaced with one that worked the turbo boosted nice and clean up to around 6 - 7 PSI. At this point I finally broke down and brought it to a mechanic and he claimed that those boost levels were "normal", he also loosened the wastegate and claimed that that should help. I did notice a bit more boost at the lower RPM's but still only boosting to 6 - 7 PSI. Since I have replaced just about every other darn part on the thing I decided to clean the MAF sensor. At this point I was running out of parts to replace ... I noticed that the "potted" part of the sensor was cracked and the plastic had shrunk. I cleaned the sensor anyway with CRC SensorKleen. Well! it worked! I am finally boosting to 9.5 PSI and the car really hauls!

Thanks to everyone for all your help.

I was thinking of playing with one of the TLAO tunes. I have installed a socket in my spare ECU and am itching to start to try some new tunes!

[Naughty33W]

fasteddie042, on 24 December 2009 - 04:59 AM, said:

I noticed that the "potted" part of the sensor was cracked and the plastic had shrunk. I cleaned the sensor anyway with CRC SensorKleen. Well! it worked! I am finally boosting to 9.5 PSI and the car really hauls!

"potted" ?

[fasteddie042]

In hindsight I don't know why I put potted in quotes, it must have been the celebratory beer. Anyway potted electronics are basically electronics that are covered with epoxy.