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VL Rough Idle, Stalls under acceleration!

markER717

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Hi all, bit stumped here hoping for some help. My RB30 VL is running awfully, it will start fine, but will idle very low and rough. If you stab the throttle it will pick up, but if you rev slowly it will splutter and stall. I have replaced the following: CAS & Plug, AFM, CTS, Injectors, Plugs, Leads, Dizzy Cap, Rotor Button, Fuel Filter, Intake manifold Gaskets. I have no idea anymore, any suggestions? I am thinking fuel pressure reg or coil? Would timming issues do this?
 

87RB30VL

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Take the dizzy cap off and spray inside it with innox / wd40 and clean the points on the inside, sand them if there's buildup of crap on them. That's what mine was doing till' I pulled the cap and cleaned the points, ran fine since then. Also if you've changed heaps of parts, try taking your negative wire off the battery for 10 - 15 minutes to reset the ECU, then put it back on and let the car idle for a bit to reconfigure. I had to do that after I changed my CAS and AFM since my car was spazzing out, not revving over 2000 etc
 

markER717

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Take the dizzy cap off and spray inside it with innox / wd40 and clean the points on the inside, sand them if there's buildup of crap on them. That's what mine was doing till' I pulled the cap and cleaned the points, ran fine since then. Also if you've changed heaps of parts, try taking your negative wire off the battery for 10 - 15 minutes to reset the ECU, then put it back on and let the car idle for a bit to reconfigure. I had to do that after I changed my CAS and AFM since my car was spazzing out, not revving over 2000 etc


Took the dizzy cap off, and they where a bit corroded (didn't think to do that sooner as it was a new cap!), so I did what you said and cleaned them up and idled perfectly until I have it a bit of throttle then it died. Noticed the big air line on the intake pipe had fallen off so refitted that and was working perfectly for about 5 minutes then gave it throttle and started carrying on again. It won't idle properly will hover between 600rpm to about 1200rpm, but off idle it runs okay. Had the battery disconnected last night as you said and so I ran it a while til it went up to about half way temp but it didn't change and I didn't want to leave it any longer as the thermos aren't wired up properly at the moment. Any other ideas mate? I will be checking the timming when I can get a hold of the light. I have the vac line for the aircon controls disconnected would this have that drastic of a problem?
 

jatsvl

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just more sugestions,
make sure the aac valve is clean and moving freely,
a dirty throttle body will play up with light acceleration, so clean the inside of your throttle body with carby/throttle body cleaner (use heaps of it)and a tooth brush,scrub all around.
for a better clean it is recommended to remove the throttle body and give it a good clean off the engine but the above method is effective.
 

87RB30VL

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+1 on cleaning the aac. As for the air con being disconnected, I'm no expert but any vacuum leak is a bad leak, so it could have an effect on it, then again it could be fine, I'm not 100% sure. Check your intake piping as well for leaks and cracks, also that big line on the intake, make sure it's securely in as they're prone to leak where it goes into the intake pipe
 

markER717

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just more sugestions,
make sure the aac valve is clean and moving freely,
a dirty throttle body will play up with light acceleration, so clean the inside of your throttle body with carby/throttle body cleaner (use heaps of it)and a tooth brush,scrub all around.
for a better clean it is recommended to remove the throttle body and give it a good clean off the engine but the above method is effective.
Thanks mate, throttle has already been cleaned and I have fitted a clean known good AAC. Any other suggestions? :)

+1 on cleaning the aac. As for the air con being disconnected, I'm no expert but any vacuum leak is a bad leak, so it could have an effect on it, then again it could be fine, I'm not 100% sure. Check your intake piping as well for leaks and cracks, also that big line on the intake, make sure it's securely in as they're prone to leak where it goes into the intake pipe
As above done AAC and TB. I have checked for vacum leaks, all hoses are on, I reconnected the aircon controls so its not that. I checked the ignition timming but I couldnt get it to sit in the correct revs as it jumps around too much on idle and fitted brand new spark plugs. The car will fluxuate between 600-900rpm now on idle, because it appears to be missing, but runs fine off idle without load. Any more ideas guys? this is driving me nuts.
 

Scrusy

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Try the fuel regulator. I had a similar problem to what u described. And that's all it was to be replaced. $170 from repco
 

markER717

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Try the fuel regulator. I had a similar problem to what u described. And that's all it was to be replaced. $170 from repco

I'm leaning towards that as well, as its more or less the only thing that hasn't been replaced. Its not logging any fault codes on the ECU either which sucks. Anyone know if there is anyway to test the pressure regs on these?
 

87RB30VL

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Any ideas/tests I could do that wont involve a changing parts and could possibly narrow down the issue?

Take it to a mechanic I guess. You gotta remember, these cars are what, 25 or something years old, so half the parts on there are crappy anyway so you might as well fork out a few bucks for a part now, and potentially fix the issue, or keep trying to trouble shoot, but I can't think of anything else you haven't tried
 
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