What the hell is wrong with my car???

[Steviekid]

I've had turbo problems since last summer and I just don't know what to do next . The problem was initially that the first turbo would come on, get to about 0.6 bar, then the boost would drop off and the second turbo wouldn't come on. This was very inconsistent though and didn't happen all the time. Sometimes if you released the accelarator and stamped on it again it would boost ok to 0.9 bar. Occasionally it would also spike to 1.4 bar+

 

To cut a long story short, the car has been in and out of the garage since. The turbos have been off (both fine), all the vacuum hoses changed and sequential valves and VSV's checked with nothing wrong found. It's been in TTC since as that makes the boosting consistent but its low at 0.7 bar and very laggy. A ball and spring MBC was difficult to set and inconsistent.

 

Last weekend I fitted a Greddy Profec B Type II EBC. With the setting at 0% the car only boosted to 0.55 bar. Adjusting the controller consistently raised the boost until it reached 0.9 bar at 52% but after this there was no increase in boost at all. This morning I fitted double de-cats with a 1.25bar restrictor ring (leading into a nur spec) and it has made absolutely no difference, still 0.55 bar at 0% and 0.9 bar maximum. :cry:

 

Does anyone have any ideas? Please help!

[ellis]

Sounds like a Chris Wilson technical one this.

[Pete]

Well out of my knowledge, but my bet is on split pipe or faulty actuator somewhere. (I know you said they were tested, but it wouldn't be the first time one garage said something was ok and another not.)

 

If it's only hitting a limited top pressure then a pipe may be leaking stopping any more pressure build up. The spike you saw may have been a fluke where the leak stopped for some reason.

 

I'm not sure where you'd start looking with all the network of pipes on there! Maybe the old washing up liquid test will help you find it. Of course it may only show up under boost.

[JohnA]

I'm always sceptical when (non-specialist) garages say that they have taken the turbos out and checked 'everything'.

I wouldn't be surprised if they didn't know what to check for.

Example: did they manually pressurise the actuators to see if they react at the right pressures?

Do they even *know* what these pressures should be?

[Suprasteve]

this may help...

 

(copied from http://www.mkiv.com/faq/faqtt.html)

 

 

7. my car won’t boost very high. it stumbles and lets out black smoke while accelerating. what is wrong? i have the stock mass air sensor (maf).

regardless of how bad it looks, it’s a simple thing to fix. air metered by the maf is leaking out somewhere, causing the computer to dump more fuel than is necessary to move the car.

 

first thing is to check all the hoses and intercooler pipes. make sure each connection is tight, and follow the hose diagram on the underside of your hood to make sure all the smaller hoses are attached correctly. if everything appears to be in good order, you need to do an intake leak test.

 

the primary method of doing an intake leak test is to remove the intercooler hoses to the throttle body and the turbo outlet pipe. plug both ends, pressurize the system and listen for leaks. it helps to splash soapy water on the pipes to spot the leaks.

 

some people perform intake leak tests by plugging the intake and capping off the pcv hose from the exhaust cam cover. if you do it this way, do not be alarmed if a lot of pressure is mysteriously disapearing. some pressure can escape due to valve overlap, especially with aftermarket cam gear(s). if you suspect this is happening, try turning the motor over a little bit and see if it stops.

 

if the stock hose clamps just don’t seem to be working well enough, get t-bolt clamps. you can order them from http://www.mcmaster.com or buy them from napa (they are listed as heavy duty hose clamps).

 

stock ic's need 10 clamps (9) 2.75 inch, (1) 3.25 inch

 

fmic's need more then 10 usually. (1 or 2) 3.25 inch and the rest are all 2.75 inch.

back to start

 

8. my second turbo doesn’t kick in immediately after i downshift. what is wrong?

its probably the pressure tank. Check to make sure the 1/8” hoses leading to the iacv and egcv have pressure in them. if not, your pressure tank is probably bad.

 

9. my boost is acting strangely, and i do not have a boost leak. what could be wrong?

do you really not have a boost leak? an intake leak test is the only way to be sure.

 

if not, the first thing to check is the hoses. see the hose layout diagram on the underside of your hood? make sure all the hoses listed there are connected properly. the main culprits are the smaller 1/8" hoses that attach to the intake air control valve and the exhaust gas control valve. some are hard to get to, just remove whatever you need to check them all.

 

if all the hoses are in good shape, then the next thing to check is the solenoid valves (vsv's) themselves. the vsv for the intake air control valve (iacv) is located near the firewall on the left side of the motor. it's connected to a 1/8" vacuum hose which attaches to a hockey puck looking thing (the iacv actuator). when the vsv is not powered, it should not allow air to pass through it. the side attached to the metal mesh of pipes should be blocked, and the side attached to the actuator should vent to the atmosphere.

 

the vsv for the exhaust gas control valve (egcv) should perform exactly the same, but it is harder to get to. it is located directly behind the wastegate vsv, with one 1/8" hose going straight up and another going straight back.

 

if the vsv's check out ok, the next thing to check is the pressure tank. the 1/8" lines leading to each vsv should be pressurized at all times by the pressure tank. if these lines aren't pressurized when you remove them, its likely the pressure tank is bad.

 

if the pressure tank is ok, next try testing the actuators themselves. apply air pressure to each actuator (the hockey puck looking things attached to the vsv's, 10 psi should do it) and ensure that they are not leaking and correctly actuate their respective valves. for the iacv, this can be easily seen. the egcv is harder to see, but it can easily be heard if you have an aftermarket exhaust (the exhaust note will get deeper and louder). if the actuator arm on the egcv breaks, the exhaust will rattle excessively (note that some rattle is normal with aftermarket exhausts) and the car will not boost well at low rpms.

 

some people perform the temporary ttc mod to troubleshoot boost problems. if the problem is the iacv vsv, egcv vsv or the pressure tank, the temporary ttc mod will fix the problem.

 

note that any malfunction of these parts is suspected to lead to sudden second turbo failure, also known as the death whine. if your car produces exactly zero boost when the second turbo is supposed to kick in, has an excessive amount of oil in the intercooler pipes, and makes a sound like this, then you second turbo is probably blown, sorry.

 

for more information on the supra's sequential turbocharger system, see pages 88 to 95 of the ncf.

 

10. how do i to trouble shoot the sequential system?

as you can see from the discussion in number 1 above, the operation of the sequential system is complicated and requires all it s components to be functioning properly. failure of a component will cause the disrupt the proper sequential operation of the turbos and can lead to failure of one or both of the turbochargers.

if any of these valves aren't working properly, you'll have low boost problems:

 

1. bov (boost will get bled back to intake)

2. ebv (loss of exhaust energy)

3. egcv (loss of exhaust energy)

4. wg (loss of exhaust energy)

 

now if the egcv, or ebv aren't working properly, you should have strange transition problems, as well as low boost on the low end.

 

if the problem is the wg, you should suffer low boost consistently, whether it's only #1 or 1+2.

 

one way to sort his out is to put the car into true twin conversion (ttc) as a diagnostic tool. (ttc instructions) if your boost problem goes away with ttc it has to be one of the vsv or actuators that is malfunctioning. ( as an aside many list members feel that ttc is safer for your turbos because by eliminating the sequential operation eliminates the chance that the turbo will boost against a closed valve and twist the shaft).

 

the actuators can be checked in the car. all you need to do is hook up a pressure source (i use a 60cc veterinary syringe) and pressurize the actuator, then watch to see if it leaks down. it's pretty simple. don't go over 20 psi with this as you'll blow an actuator diaphragm or overextend an arm.

 

the vsv's are the same. hook up pressure to see if they leak. then apply a ground to the wire going to the ecm to actuate the vsv and see if it opens. of course they are not all normally closed, so you may need to check flow just the opposite.

 

if it's on the compressor side, it could be your bov passing at low boost. these are easy to check and just need a source of vacuum. there is the suck and blow test… suck on the smaller tubing while a friend blows down the larger tubing. if he can blow through with out resistance it is normal. if he cannot blow through while you are not sucking that is normal operation.

 

another possible source of the problem is a vacuum leak. the newest of the supras are 4 years old as this is written (jul. 02) the oldest is 9 years old. the various rubber control lines get brittle and leak. the leaks may not be obvious to a superficial look. i suggest replacing them with silicon vacuum hose which has the additional benefit of looking great. short of that if you suspect that is the problem pull the individual hoses to inspect them .

[Alex]

I'm guessing but I'd investigate all the pipework to and from the pressure tank under the intake manifold and the pressure tank itself.

 

(And that was without reading the post above which appears to confirm that)

[Steviekid]

Just stuck it back in sequential. Slow boost increase to 0.3-0.4 bar then it drops a bit then boosts up to 0.9 bar tops if you hold the pedal to the floor.

 

I'm away to get some wire to hold the IACV and EGCV's permanently open regardless of the pressure/lack of pressure they see, to see what happens.

 

The car was at a specialist performance garage btw! I wouldn't let toyota near it!

[Steviekid]

I'm guessing but I'd investigate all the pipework to and from the pressure tank under the intake manifold and the pressure tank itself.

 

(And that was without reading the post above which appears to confirm that)

 

I've been a bit suspicious about the pressure tank for a while. If that's the problem then wiring the actuators open would make the problem go away wouldn't it?

[JohnA]

if the pressure tank can't hold pressure properly, then the actuators won't be left open as one would expect them to.

 

For anyone who knows jack shoite it's easy to troubleshoot these faults, all it takes is a T-connector and a boost gauge.

Then eliminate the actuators one by one.

It's not rocket science.

[Pete]

It's not rocket science.

It is if you've never done it before and you're faced with a pile of piping that if you take it off you're not sure it'll even go back on...or they're attached with connections you've never even used before.

It's all relative.

[Suprasteve]

It is if you've never done it before and you're faced with a pile of piping that if you take it off you're not sure it'll even go back on...or they're attached with connections you've never even used before.

It's all relative.

 

got to admit, I wouldn't have a clue where to start or what to do...but then i do sit behind a desk for a living.

[JohnA]

It is if you've never done it before and you're faced with a pile of piping that if you take it off you're not sure it'll even go back on...or they're attached with connections you've never even used before.

It's all relative.

yes of course, but we're talking here about a garage that claims to have already checked these things. Professionals.

 

We're not talking about a man from the street --- the system would then appear fearsomely complicated, even you tried to explain to him how it works.

[Pete]

yes of course, but we're talking here about a garage that claims to have already checked these things. Professionals.

 

We're not talking about a man from the street --- the system would then appear fearsomely complicated, even you tried to explain to him how it works.

Ah - Sorry John. I took your post to mean that Steviekid was

being a divvy for not doing it.

I agree - should be well within a decent mechanics ability...but then these are hard to find too.

[JohnA]

A 'decent' mechanic would be out of his (her!) depth with the TT sequential, it is a specialist subject.

 

I explain the way it works on my site, and despite using several diagrams, abstractions and pictures, it's still bound to give you a headache first time round.

 

No, I wouldn't trust a 'decent' mechanic around all those actuators, I'd like a specialist.

[supRo]

As above, get the Boost pressure tank checked out Steve. I've had the same symptoms before and mines turned out to be the boost pressure tank,

 

I reccommend taking it to Thor to get your car checked out.

[INDYPWR]

i too was using the gredd profec b II...i hated it because it was to hard to adjust.....very complicated EBC.

 

when i had it, i was hitting 1bar even 1.2bar and get fuel cut.

i was also getting boost creep, adjusted the EBC a lot but still didnt get the right specs. my boost would drop and climb back up as well.

 

so, i took out EBC and FCD and now i am hitting consistent 14psi

with both decatts; no restrictor ring though.

 

my set up is different from others here. i swapped aristo jspec motor on my soarer.

[Steviekid]

Right, I've just wired the IACV and EGCV fully open (both of which smoothly opened and stayed open with ~10psi of pressure from a foot pump). I also blocked the pressure tank pressure feed pipe off in case there's a leak round the tank although there is definately pressure coming from it to both the IACV VSV and the EGCV VSV as you can hear it being released when removing the hoses.

 

With both valves wired open the car was exactly the same, 0.55 bar at 0% on the EBC up to a maximum of 0.9 bar. Can someone confirm this means there is no other explaination for lack of boost other than a leak in the turbo>SMIC>intake section? All sequential/VSV/pressure tank problems would have been eliminated by the above wouldn't they?

 

Steve

[Steviekid]

Ok, did this tonight:

 

 

Blew it up to 1 bar. Virtually no pressure drop, lost about 0.1bar in an hour (tube expansion??). Surely thats not enough of a leak to make my car run 0.55 bar with double decat?

[Suprasteve]

Ok, did this tonight:

 

 

Blew it up to 1 bar. Virtually no pressure drop, lost about 0.1bar in an hour (tube expansion??). Surely thats not enough of a leak to make my car run 0.55 bar with double decat?

 

I had a double take at that picture to workout what the hell it was ! - bet the neighbours were wondering too.

[Guest nicksri]

Disconnect the EBC and try again to see what happens. With both IACV and EGCV wired open, you should get no booth until around 2,500 rpm. The highest boost should be around 0.8 to 0.9 bar with cat off.

 

When your car was in sequential, at around what RPM the boost dropped off?

 

If you have a T-connection and a boost gauge like John said, you can trap the pressure from between the IACV and the IACV VSV. The gauge should read 0 until you accelerate to over 4k rpm the gauge should register boost pressure and when you take you foot off the pedal, the gauge should stay at certain reading for about 3 seconds before coming back to 0. If this happens, your IACV and IACV VSV is OK. Do the same to the EGCV and EGCV VSV. Then get the pressure from between the pressure tank and the IACV VSV (you can trap the pressure from the IACV VSV side, not the pressure tank side). Once you have boost, your gauge will read the highest pressure you make and stay there (the pressure will very slowly decrease which is OK). If this happens, your pressure tank is OK. Then, you can check the EGBV by running on only turbo #1. Everything as original, you remove the lines that feed IACV VSV and EGCV VSV and plug them. By doing this, the IACV and the EGCV will remain closed. You will be on turbo#1 only. Then, remove the line from turbo#1 compressor housing that feeds the wastegate and plug it. By doing this, you will only have the EGBV to operate as the only wastegate for turbo#1. Go for a spin and see what you get on the boost gauge (reading the pressure from the intake manifold). Be careful though because if your EGBV does not work and remains closed, you will easily get runaway boost because you have no wastegate to control the boost at all. If you have 0.6 bar, your EGBV works OK. Then, check the wastegate. Everything as original, you remove the pressure feed line (the one that goes to the EGBV and the pressure tank) and plug it. By doing this, the IACV, the EGCV and the EGBV will remain closed. Go for a spin and see what happens. You will find it very difficult to reach some areas.

 

If everything checked out OK and you still have a boost drop at 4k rpm when you are on sequential and you have consistent boost when you are on TTC, you are on the same situation as mine. I am still trying to figure out where the boost can go. I get the pressure reading from the turbo#1 compressor housing, not from the intake manifold where the pressure drop can be from leak hose or leak intercooler. When I am on sequential, I got 0.6 bar of boost up until 4k rpm when the boost dropped to 0.2 bar and stay there until the gear change. I have no problem when I am on TTC. Where can the boost go?

[Steviekid]

Cheers for the help nick, sounds like slightly different symptoms though. In sequential I get the first turbo coming on making 0.5 to 0.6 bar at the very most, boost then drops down to around 0.3, but does come up again when second turbo comes on but only to 0.8 -0.9 maximum (higher than it did before I fitted the EBC). The maximum boost I can reach in TTC compared to sequential is the pretty much the same, the only reason I'm in TTC is to avoid the bad power drop before turbo 2 comes on in sequential. I was convinced that there was a boost leak round the intercooler somewhere that was limiting the pressure turbo 1 could create (hence the reason it was running out of steam before turbo 2 came on line and why both together couldn't make over 0.9bar). Now that I've eliminated that I don't really know where to go next.

 

I'll try some of the things you've suggested (have done some of them already) but problems with the IACV/EGCV/pressure tank wouldn't stop the car boosting properly in TTC? The EGBV wouldn't open either with the pressure feed blocked off. What boost can you reach in TTC?

 

Was going to work on the car again today but it looks like this!!

 

[JohnA]

...problems with the IACV/EGCV/pressure tank wouldn't stop the car boosting properly in TTC?..

I can't imagine what sort of answer you'd expect for this question.

Or is it a statement?

Because in that case it is incorrect. A malfunctioning pressure tank would not allow the IACV and/or EGCV to open properly (if at all) leaving turbo#2 outside the loop.

[Steviekid]

I can't imagine what sort of answer you'd expect for this question.

Or is it a statement?

Because in that case it is incorrect. A malfunctioning pressure tank would not allow the IACV and/or EGCV to open properly (if at all) leaving turbo#2 outside the loop.

 

If I was running TTC by bypassing the VSVs yes, but both the IACV and the EGCV are permanently wired open at the moment with the pressure tank pressure feed blocked off. With no improvement surely this eliminates them as the problem?

[dangerous brain]

 

Was going to work on the car again today but it looks like this!!

 

 

 

Whats your problem man??? Get out there ya pussy :D

[JohnA]

Maybe I'm missing something here.

The 'wired' versions I know of still use the pressure tank to push the actuators into the 'open' position.

Are we talking here about another, permanent way of keeping the valves open? (mechanical intervention perhaps?)

 

Because if you have just wired up the VSVs then you still expect boost pressure to move the actuators, don't you?

 

Does this make sense?