Yak's Time Attack Nissan 200SX S13

[Yak]

Ah, I feared you might say that. Its buried right down behind the suspention turret because of how shot that bit of loom is 

Managed to get to the car early enough to fire it up toay. Altered the next row timing down to 15. this seemedto smoooththe idle a fair bit.
With the ICA dissconnected I get the warm idle to about 1000rpm with a bit of hunting. But no matter what i set the idle to using the screw whhen i plugged the ICA it didnt make any diference 

[rob@vems.co.uk]

It should make a difference when cold, as the valve will start open and PWM itself closed in a nice progressive (if tuned nicely) manner.

Idle is a sod to get right, I've spent ages getting mine to idle nicely, it kind of does now, but thats taken a load of work with springs and throttle plates and so on.

Rob

[Yak]

PWM? Am I unplugging the correct thing? Must be as there aint anything else the VEMS controls around there?

May be the valve isnt working. I can hear it clicking away when the ignition is on but it had no noticeable effect on the idle no matter what i set it too with the screw.

I can see a smooth idle being hard to set up but all I want is it to not stall all the time when its hot. I realise now that the test last night was a bit fake as the bonnet was not on the car at all.

Any ideas what my bad on boost miss fire could be? Im beginning to wander if the FPR is on its way out as I could smell petrol when it was missing on the motorway... or may be an injector seal. Arg.

[rob@vems.co.uk]

If you hear it clicking when the ignition is on then the solenoid is firing (btw to stop it clicking when the engine is not running go to Extras->Idle PID ref table, PWM and set the entries under IAC position while starting to 100 to have the IAC fully open when starting or 0 to have it fully clothed.
Have you tried fiddling with the Idle control IAC position reference table in that screen to adjust the throttle position?  If you set them all to 100 then the IAC should be open all the time, once again setting them to 0 will close it - this will help diganose the operation of the IACV.

[Yak]

Nope not played with that yet as I didn't know what it did. Think i see the idea now but the data in it seems a bit odd. In the main ref table the values go:

70
65
60
55
50
45
40
35
50

Would you not think the last, warmed up cell would be 30?

I will have a play with that table tonight and see if the valve is broke and swap it if needed.

Any way have made some progress now. Have left the IAC unplugged for the moment as it didn't seem to do anything. But I have now powered the OE cold fast idle valve from what would have been the power to the fuel pump (the fuel pump now has a direct feed from the battery) so that valve should be shut when warm. Now the car will hunt when warm but will actually idle and stalls a lot less often
Also replaced the fuel pump and filter. and when inspecting the boost lines found one had started to split around one of the reducer joins to get it on to the back on the vems. I have replaced this now by just forcing the bigger tube over the threaded part of the senor on the vems and zip tyeing it!
Took it out for a short run and this seems to have curred the bad miss fire I was getting on boost

Had a look at the data log and it is still getting wobbly RPM. But I think I have got loom issues as the laptop started throwing configuration string error warnings until I unplugged and replug the vems. Then it would not start and it seemed to have lost the CAS signal completely and was not seeing any RPM at all. Again prodding around at the loom and plugging the vems back in solved this so I think I will run a new shielded cable to the CAS directly from the VEMS.
Any recommendations of what cable to use?

[rob@vems.co.uk]

You need 4 core screened cable, I'd suggest this: http://www.maplin.co.uk/Module.aspx?ModuleNo=137&doy=4m8&C=SO&U=strat15 but ideally the cores would have a larger diameter.  Are there any audio shops near you?  The ideal stuff is the stuff they use for stage audio as its tougher than home stuff.

I use http://www.maplin.co.uk/module.aspx?ModuleNo=133&doy=4m8 for the REF and POS CAS signals on the adaptor you have, if you were to get two lengths of this, join the screens together and ground them on one of the CAS bolts with a ring terminal, then use the four for REF, POS, +12v and ground you'd have a pretty well shielded connection.
What ever you do dont disconnect the ground wire on EC36pin26 from the ground cluster.  Connect the REF and POS signals to the EC36 pins, the +12v should be fed from the ECCS relay (there is a spare ECCS pin on the connector) and the ground wire should join the ground cluster on the harness adaptor.

Also dont underestimate the amount of effort required to get the adaptor and loom plugs to connect together well, that bolt has to be mega tight and its not a bad idea to use cable ties through the 3 screw holes on the male plug to pull plugs tight and ensure they dont 'walk' apart.

[Yak]

K, got 2 lots of the 2 core cable and a load of 6mm ring connectors (as never seem to have enough of them. Not wired it up yet though.

Had a play with the Idle control IAC position reference table and the idle control screw last night. Got it to idle quite nicely when warm and turned the lambda control off when idling... unfortunately it seem to have messed up the cold idle now! lol. Don't think its getting enough air so either the cold idle valve still is not working correctly and / or the idle control valve is not open enough so the IAC can not let enough air in for cold idle... I think.

Still I was quite surprised how you can control the idle speed by tabbing between fields on the laptop. I was expecting to have to burn the settings to the VEMS before they take effect

Its also sooooo nice not to have to keep bliping the throttle when pulling up at a junction.

[Yak]

Well the idle ain't bad at all now but...


AAAAAAARRRRRRRRRRGGGGGGGG the on full boost miss is back again. Though the fuel pump / filter / boost hose change had fixed it but is back again.
Its less of a miss, more of it feels like its holding back and making a constant purring type noise and it just does not want pull. It does pull through it but very slowly.
Checked fuel pressure yesterday and adjusted it so reasonably confident that fueling is OK. I think if it was that bad it would have melted a piston by now.
New plugs, another set of coil packs, new CAS wiring in and its not making any difference. I'm running out of idea unless its a fault in the vems unit?

[gunni]

What

Boost
LAmbda at said boost
type of coils and external amp?

[rob@vems.co.uk]

Damn shame we didnt get datalogs when it was good to test it when it was bad.
I'm not sure how we can point at the VEMS as being a problem, but we can do all we can to test it and find out what your issues are.

[Yak]

Well only that its one for the few parts in the ignition system that we have not tried swapping yet.

Well the brands event created more issues... After staying up till the early hours with Kev on Friday night we found the car would run fine as long as it stayed under 20PSI. Actuator pressure on it at the mo is 16/17 PSI so at least I had something I could race with on Sunday.

On Sunday morning we tried raising the boost up to 20PSI as I was soooo slow compared to the other cars on the straights. Kept turning the force duty up but it made no difference. Tried plugging the solenoid into SMs car and found it would fire when testing it. Testing on mine it just clicked once.
Is the signal from the VEMS meant to oscillate between 0 and 12 volts? As it seems to be a flat 12V when we tested it with a multi metre.

So resorted to a old school bleed to bring the boost up. This seemed to work quite well. brought the boost up to 20PSI... until I think I straddled the exit Kirby on graham hill bend and bounced the exhaust of it. Came in to the pits a few laps later with only 3PSI of boost, 3 badly stretched turbo to manifold studs and one completely missing!

Tried to do a stud swap in the 2 hours over lunch... unfortunately lunch was cut short by 30 mins so didnt get back out for the qualifying session Though did get the car running again before the finals, was very close to making it out in the qualifying session.

Ive had a better quality manifold and down pipe waiying to go on, but havnt had the time to fit them. Have to now as the current manifold is scrap.

Will this cause to big a difference to the map that is in the VEMS at the mo?

[rob@vems.co.uk]

Well only that its one for the few parts in the ignition system that we have not tried swapping yet.

True, but as you found that replacing a split hose made the problem go away for a short while It does suggest that it might be related to that.

Well the brands event created more issues... After staying up till the early hours with Kev on Friday night we found the car would run fine as long as it stayed under 20PSI. Actuator pressure on it at the mo is 16/17 PSI so at least I had something I could race with on Sunday.

Where are you getting the pressure reading from?  If its a sperate boost reading Are you able to compare the kpa values in the datalogs with the peak boost that you're seeing on the gauge?  If there is a leak it might only start over a certain pressure.

On Sunday morning we tried raising the boost up to 20PSI as I was soooo slow compared to the other cars on the straights. Kept turning the force duty up but it made no difference. Tried plugging the solenoid into SMs car and found it would fire when testing it. Testing on mine it just clicked once.
Is the signal from the VEMS meant to oscillate between 0 and 12 volts? As it seems to be a flat 12V when we tested it with a multi metre.

So you've tried the same solenoid on yours and Kevs and it behaves correctly on Kevs?  When its pulsing it will oscillate, it will obviously change depending on boost pressure.  Can you pull the EC36pin plug off the VEMS and measure resistance between the 12v feed on the four pin plug and the wire that grounds the boost solenoid (its one of the FET pins I dont remember which off the top of my head).

So resorted to a old school bleed to bring the boost up. This seemed to work quite well. brought the boost up to 20PSI... until I think I straddled the exit Kirby on graham hill bend and bounced the exhaust of it. Came in to the pits a few laps later with only 3PSI of boost, 3 badly stretched turbo to manifold studs and one completely missing!

Tried to do a stud swap in the 2 hours over lunch... unfortunately lunch was cut short by 30 mins so didnt get back out for the qualifying session Though did get the car running again before the finals, was very close to making it out in the qualifying session.

Bugger, thats not going to help the fault finding

Can we recap on the way the MAP tube is connected to the ecu?  From the manifold to the VEMS.

Ive had a better quality manifold and down pipe waiying to go on, but havnt had the time to fit them. Have to now as the current manifold is scrap.

Will this cause to big a difference to the map that is in the VEMS at the mo?

That's almost impossible to say, if you get better midrange VE you may find that you get detonation as the advance may be too much, or you might just find that it runs a little lean.
If you're taking the manifold off to repair the studs you'd be better off replacing the manifold.

[Yak]

Well only that its one for the few parts in the ignition system that we have not tried swapping yet.

True, but as you found that replacing a split hose made the problem go away for a short while It does suggest that it might be related to that.

I am begining to think that one of the duel valve springs may have broken and I am getting valve bounce / float over a certain boost. Its only a theory but the symtoms match very well and it is not an obiouse fuel or spark issue.

Well the brands event created more issues... After staying up till the early hours with Kev on Friday night we found the car would run fine as long as it stayed under 20PSI. Actuator pressure on it at the mo is 16/17 PSI so at least I had something I could race with on Sunday.

Where are you getting the pressure reading from?  If its a sperate boost reading Are you able to compare the kpa values in the datalogs with the peak boost that you're seeing on the gauge?  If there is a leak it might only start over a certain pressure.

Unfortuantly no. I really must fix this and totaly rearange the boost lines in the car. Whould a boost leak effect the vems as its MAP rather than MAF basid?

On Sunday morning we tried raising the boost up to 20PSI as I was soooo slow compared to the other cars on the straights. Kept turning the force duty up but it made no difference. Tried plugging the solenoid into SMs car and found it would fire when testing it. Testing on mine it just clicked once.
Is the signal from the VEMS meant to oscillate between 0 and 12 volts? As it seems to be a flat 12V when we tested it with a multi metre.

So you've tried the same solenoid on yours and Kevs and it behaves correctly on Kevs?  When its pulsing it will oscillate, it will obviously change depending on boost pressure.  Can you pull the EC36pin plug off the VEMS and measure resistance between the 12v feed on the four pin plug and the wire that grounds the boost solenoid (its one of the FET pins I dont remember which off the top of my head).

Will do. No, we had the lap top to turned the "Turn off the controler below this presure" down to 0 so the solinoid will start clicking away. Doing this on Kevs car it clicked away happily. On mine it was silent.

So resorted to a old school bleed to bring the boost up. This seemed to work quite well. brought the boost up to 20PSI... until I think I straddled the exit Kirby on graham hill bend and bounced the exhaust of it. Came in to the pits a few laps later with only 3PSI of boost, 3 badly stretched turbo to manifold studs and one completely missing!

Tried to do a stud swap in the 2 hours over lunch... unfortunately lunch was cut short by 30 mins so didnt get back out for the qualifying session Though did get the car running again before the finals, was very close to making it out in the qualifying session.

Bugger, thats not going to help the fault finding

Can we recap on the way the MAP tube is connected to the ecu?  From the manifold to the VEMS.

Currently, badly probably.
The Map tube is attached to the manifold via the nipple just behind the throttle, then goes to the back of the bay, accross the back wall of the bay, out the left inner wing and then into the cabin via the back of the wheel well. Where it Ts with the manual boost gauge and then to the VEMS its self.
Mmmm, Yeah that sounds bad!

Ive had a better quality manifold and down pipe waiying to go on, but havnt had the time to fit them. Have to now as the current manifold is scrap.

Will this cause to big a difference to the map that is in the VEMS at the mo?

That's almost impossible to say, if you get better midrange VE you may find that you get detonation as the advance may be too much, or you might just find that it runs a little lean.
If you're taking the manifold off to repair the studs you'd be better off replacing the manifold.

Aye, its only possible to put 2 studs and one nut and bolt through that manifold now

[rob@vems.co.uk]

I am begining to think that one of the duel valve springs may have broken and I am getting valve bounce / float over a certain boost. Its only a theory but the symtoms match very well and it is not an obiouse fuel or spark issue.

Well its possible, but that wouldnt explain the "intermittent fix" caused by replacing the split hose.

Unfortuantly no. I really must fix this and totaly rearange the boost lines in the car. Whould a boost leak effect the vems as its MAP rather than MAF basid?

Massively and completely, as its a primary sensor its vital that it gets the correct pressure or the ECU will not calculate the engine load correctly - which could be disaterous.

Will do. No, we had the lap top to turned the "Turn off the controler below this presure" down to 0 so the solinoid will start clicking away. Doing this on Kevs car it clicked away happily. On mine it was silent.

Did you use the flyback diode?  That will stop the clicking.  The fact you've had some success with this before is significant.

Currently, badly probably.
The Map tube is attached to the manifold via the nipple just behind the throttle, then goes to the back of the bay, accross the back wall of the bay, out the left inner wing and then into the cabin via the back of the wheel well. Where it Ts with the manual boost gauge and then to the VEMS its self.
Mmmm, Yeah that sounds bad!

You're frightening me now!  The MAP sensor is of primary importance and should never be shared with any other device, I've seen the aftermath (a head destroyed) of when a boost guage failed and started bleeding air so that the ecu saw a fraction of the boost pressure that was acutally being produced.  The boost controller kept the bleed open (as it was reading low boost) the ecu kept the ignition advance up (for the same reason)...  It wasnt a VEMS install but the laws are the same.  What was done to make sure it never happened again is what I'd suggest now:  Find a local pneumatic supplies place, there are hundreds of them about, and get a threadedpush-fit fitting: that will take the correct tube for your ECU, for the boost guage and for the turbo's wastegate, fuel pressure regulator, drill and tap the manifold for them and block the rest of the holes off.  Then run one tube per item. I've been to a couple of places and always found the blokes to be helpful and interested (because they dont tend to see car applications).
Then not only will you have a proper setup, it looks the business too.
I'm not saying that this will solve the problem but... its the correct way to do an install.

Aye, its only possible to put 2 studs and one nut and bolt through that manifold now

So your car cant have been that slow in order to hit it that hard   I saw your lap times and they werent too awful.

The next ones at Snetterton isnt it?  Thats my local track, let me know the date and I'll put it in the diary and if the worse come to the worse I'll push your car round the track to make sure you're running

[sm]

Its 12th October @ Snetterton.

Your allowed a technician in the car for the first session, as long as they have a laptop or similar and are working on car setup. We can get you a team pass for the pits no problem