Rb20det Problems

[joe blo]

i just got a vl with a rb20det with auto gearbox in it. it was running really rough when you put your foot even lightly on the accelerator but you could still drive it ok and sometimes it will want to accelerate and other times it will hesitate and wont go very good.

so i changed the spark plugs from ngk bcpr5es -11 or whatever they are to bcpr6es (cant remember exactly right now what the letters are but there the ones everyone says to use on here) and it runs alot better but it still doesnt go good on top end and wont accelerate hard but it hardly hesitates now. i beleive the new plugs are .8mm gap or something and ones with -11 would be the same heat range but 1.1mm gap. i read to go the .8mm gaps if its got breathing mods like air filter and exhaust so i got them ones coz it has pod and 3 inch exhaust. would they be the right ones?

the guy i got it off said his mechanic said it had something wrong with the turbo but the boost guage doesnt seem to work so i cant see if its making how much boost its making but it does seem to make some but i dont know if its actually making any but it makes the dose noise louder the more you rev it out. i wasnt revving it hard at all before i changed the plugs and just revved it out a few times around the block but it wont rev very hard. there is a whining noise that sounds like supersonic is the way i would describe it like high pitched whirring noise when i park it and rev it then it wakes the noise for a few seconds. does it sound like there might actually be a problem with it not allowing it to make boost. the guy i got it off said it wont make boost but if he was just looking at the guage it doesnt move at all for vaccuum or boost.

or does it sound fuel related coz he said something about fuel regulator or fuel pump that his mechanic said?

or does it sound like something to do with the computer maybe not allowing it to rev out coz it said something about the computer in the ad but i dunno? its had water leak down in the wiring and computer but i havent opened the computer to check. is there a way to check fault codes on the computer to see if theres anything wrong?

so yeah mates, if you have any ideas let me know where to start with the cheapest options first. and i wont be driving around foot to the floor so i dont lean it out bad ( hopefully the few hits i gave it didnt hurt it. i was going with like a quarter accelerator and it would go ok then when it wouldnt go any more on quarter accelerator id give it full throttle and it would go abit more but not much. hopefully it wasnt too bad)

i spoke to the guy that did the modplate about 6 months ago and he said it had problems when he did the modplate for it ages ago. he said something about the coils. does it sound like it could be coil packs?

how would i check to see if the turbo is ok? check the front for shaft play and check to see if the rear wheel is stil intact then that would mean its ok sort of? it seems like it wants to come on boost and does abit then it all sorta flattens out.

also when i start it when the motor is cold it takes like 5-10 times for it to actually start then when its warm it goes first time everytime. does that help any to diagnose the problem?

i dont wanna take it to a shop just yet

sorry mates theres a fair bit to read there.

[White GTS-T]

There's a lot to decipher there. First of all check the basics. It could well be that the new plugs are already fouled which is why it is hard to start which could indicate a problem elsewhere. I would be disconnecting the battery negative terminal and then pulling the ECU apart to check for water damage, carbon build up, blown capacitors etc. Check the fuel pressure and flow rate with and without the vac line to the reg, also your fuel filter. Check the voltage supply to the fuel pump, i know there is something funny with the VL's in that the power supply to the fuel pump doesn't come from the ECU but from a separate relay, where as with the 32 it comes from the ECU. So something could be up there. I highly doubt the wiring for the consult port has been done but if it has and you can get it on a scan tool that could eliminate a lot of things. The wirring noise could be air getting past the rear turbine wheel, that’s if its there. Get yourself a mechanical boost gauge to see if it actually does make positive manifold pressure before you pull the exhaust off. Other than that check for vacuum leaks, check all the cooler pipes, test the primary and secondary resistance of the coils, test the airflow meter resistance, check the tps voltage at closed and wide open throttle etc. It could be many things really...the cat could be collapsed...Here's just a few things to check.

[joe blo]

thanks for that. thats the sort of stuff i wanted. i forgot to get a fuel filter when i was at the shop. like i said i want to start with the cheap stuff and free stuff first.

i can hear the fuel pump working when i turn the ignition on and after i stop the car. i dunno if it sounds bad but

i just noticed the exhaust is crushed at the end of the front pipe where it goes from the dump pipe bend then goes straight along the bottom of the car. its probably down to 2.5 inches at a guess maybe abit less. i did hit it on a driveway today but it may have already been crushed before then. il unbolt it before the cat and see how it goes. i had a vl turbo that i got with crushed exhaust probably about the same size this ones crushed to and had a collapsed cat and it wouldnt make much boost picked up 90rwhp on the dyno after removing the exhaust.

its got some defi boost guage with a seperate controller that i cant seem to get to do anything. i think il double check its actually got a hose to it. it sits on about the .2bar line once you turn the car on and doesnt move at all

how do i check the coil packs?

the idle drops when i disconnect the afm. thats a sign that its atleast working abit isnt it?

il try all that stuff but thanks.

[White GTS-T]

If the idle drops when you disconnect the AFM then the ECU must be getting the AFM signal, which is good. If the car is running on six cylinders then there's probably no point in testing the coil packs. Get the exhaust sorted, get the boost gauge sorted and go from there. Hopefully when you drop the cat the rear turbine wheel doesnt drop out. Also try a new set of plugs and see if it starts easier.

[nIsMo86]

Check the ecu for codes...theres a thread on here on how to do it. Sounds like possible coolant temp sensor issue with the starting probs you have.

Is it running standard VL fuel pump? Cause they love to break every now and then. I've been through 3 in the past on my VL