Jake Posted May 26, 2004 Share Posted May 26, 2004 My '93 JSpec Auto TT keeps cutting out for a second or two at even slightly prolonged high boost (1.2 to 1.25bar, 120mph ish) It seems rather like when it was hitting fuel cut before only it's not such a sudden, violent loss of power and also the dash warning light doesn't come on like it does at Fuel Cut. I've only been having this new problem since I replaced my faulty (leaking) BOV. I had thought that the problem might be down the NGK bog standard plugs so changed them for new Denos IK22 plugs and it seemed better for a few days, or maybe I just didn't hit prolonged high boost during those first days - difficult to say. So now I'm guessing that the problem might be the 11 year old JSpec fuel pump, does that sound like a reasonable guess? Or could I possibly need IK24 plugs? Seems unlikely for such a modest spec doesn't it? Anything else it could be? Thanks Quote Link to comment Share on other sites More sharing options...
matt Posted May 26, 2004 Share Posted May 26, 2004 Sounds like its either still hitting fuel cut .... what fcd are you running? Is it adjustable (trl or HKS) Could it be a delimiter playing up ....120 is what is usually seen when the jap limit is reached , although its really 112 (180kmh)? Quote Link to comment Share on other sites More sharing options...
Jake Posted May 26, 2004 Author Share Posted May 26, 2004 Originally posted by matt Sounds like its either still hitting fuel cut .... what fcd are you running? Is it adjustable (trl or HKS) Could it be a delimiter playing up ....120 is what is usually seen when the jap limit is reached , although its really 112 (180kmh)? Now you mention it it does seem a bit like the delimiter. I've got a TRL FCD and SLD (seperate ones) I've never changed the FCD from the default setting though. Perhaps I'd better check the FCD and SLD wiring, maybe a bad connection - they are soldiered joints though, so they should be OK. Cheers Matt Quote Link to comment Share on other sites More sharing options...
matt Posted May 26, 2004 Share Posted May 26, 2004 I believe the TRL fcd still has a raised boost cut built in ? Could be hitting that....... best ask Pete Quote Link to comment Share on other sites More sharing options...
Jake Posted May 26, 2004 Author Share Posted May 26, 2004 It does and it's adjustable even higher. If the wiring looks sound I might try raising the limit and see if the problem changes at all. I don't really want to run higher boost long term though. Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted May 27, 2004 Share Posted May 27, 2004 Originally posted by matt I believe the TRL fcd still has a raised boost cut built in ? Could be hitting that....... best ask Pete It just raises is, but when the FCD does the cut it is a normal fuel cut but at a higher boost so you'll still get the red triangle etc. Could be det? Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 Originally posted by Steve Cargill Could be det? It might be detonating but that doesn't actually cause the power to fall away suddenly and then return after a couple of seconds, does it? Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 27, 2004 Share Posted May 27, 2004 I've heard of randomly cutting in speed limiters before. Didn't you have a problem with this a while back and have to install a new unit? Any fuel cut will be harsh and light the lights. Det will give you a fade in power as the ignition timing gets retarded a huge amount but you won't get a return of power, more like your pistons exiting the exhaust -Ian Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 Originally posted by Ian C I've heard of randomly cutting in speed limiters before. Didn't you have a problem with this a while back and have to install a new unit? Yes that's right I did, I'm surprised you remeber it though, that was months ago!Any fuel cut will be harsh and light the lights. Det will give you a fade in power as the ignition timing gets retarded a huge amount but you won't get a return of power, more like your pistons exiting the exhaust So it's not Fuel Cut and you think it's not Det. So what could the problem be? Any thoughts on my original fuel pump suspicions? Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 27, 2004 Share Posted May 27, 2004 It's a knack If your fuel pump ran out of oomph at high boost you'd get det and a wrecked engine as fuel pressure and flow would fall off dramatically. I can't see any fuel pump condition causing what you are experiencing. I'd still go for a dodgy connection on the speed delimiter to start with. Not casting aspersions on your wiring skills, it's just where I'd start. You can try easing above 120mph with under 1 bar of boost. If it's fuel cut acting up, it sholdn't kick in as it only does so above 1 bar. If it freaks out around 120mph no matter how slowly you try to edge over it it's probably the limiter. -Ian Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 I'll give that a go a bit later then, cheers mate. Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 I've just been for a spin and at less than 1 bar it easily makes over 120mph. I saw 124 on the GPS at only half throttle so the SLD is working fine I guess. So then I started to gradually give it more gas to see at what boost levels it cuts out. Well, I got the car up to 136 and 1.3 bar but the damn thing didn't cut out. At the roundabout where I turned for home I gave it full throttle from 15mph up to 132lph and the power didn't fade at all. Typical isn't it? When you're trying to diagnose a problem it won't happen! Grrrr ! I'll take it out on a motorway later or tomorrow, hopefully on a motorway I'll be able to get a run long enough provoke this problem so I can see exactly under what circumstances it happens. Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted May 27, 2004 Share Posted May 27, 2004 Originally posted by Jake Well, I got the car up to 136 and 1.3 bar but the damn thing didn't cut out. It's quite a bit cooler this evening, could be the denser air affecting it. With det/plugs giving up the power and boost seems to waver about in my experience. More like a soft squidgey sort of limit not a hard on/off effect. Quote Link to comment Share on other sites More sharing options...
dude Posted May 27, 2004 Share Posted May 27, 2004 Jake i have loads of pumps if you want to try a diff one . Dude:flame Dev Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 That might be it Steve. It's definitely cooler this evening than the other times I've notice the problem recently. It can't be the plugs though can it? They're brand new IK22s What can I do if it's detonation, other than lowering the boost? Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 Originally posted by dude Jake i have loads of pumps if you want to try a diff one . That's very nice of you John. I need to come see you anyway to get a price for repainting my OSF wing and repairing/painting the rear spats I damaged. Do you still take on such poxy little jobs? What with you being all Mr Single Turbos and Widebody kits nowadays Quote Link to comment Share on other sites More sharing options...
dude Posted May 27, 2004 Share Posted May 27, 2004 Originally posted by Jake That might be it Steve. It's definitely cooler this evening than the other times I've notice the problem recently. It can't be the plugs though can it? They're brand new IK22s What can I do if it's detonation, other than lowering the boost? You could try colder plugs (IK 24's i run) !!! What gap did they have or your coils may be on the way out . Dude:flame Dev Quote Link to comment Share on other sites More sharing options...
dude Posted May 27, 2004 Share Posted May 27, 2004 Originally posted by Jake That's very nice of you John. I need to come see you anyway to get a price for repainting my OSF wing and repairing/painting the rear spats I damaged. Do you still take on such poxy little jobs? What with you being all Mr Single Turbos and Widebody kits nowadays No job too small , no muff too tuff we dive at 5 !!!! Dude:flame Dev Quote Link to comment Share on other sites More sharing options...
Steve Cargill Posted May 27, 2004 Share Posted May 27, 2004 Originally posted by Jake What can I do if it's detonation, other than lowering the boost? Brace for a big bill . . . . . Sorry, not really helpful, but could be true . . Air temps make a big difference. On really cold days you'll get a few extra lbs and on hot days you'll get less and with a much higher charge temp it can be bad for the engine (someone that can explain properly will be along shortly.....) How is your intercooler? Also, try colder plugs. Quote Link to comment Share on other sites More sharing options...
dude Posted May 27, 2004 Share Posted May 27, 2004 Jake this sounds a bit worrying , get the car to me and i'll chewck the fueling and put the Det cans on it for a blast . Dude:flame Dev Quote Link to comment Share on other sites More sharing options...
Jake Posted May 27, 2004 Author Share Posted May 27, 2004 Originally posted by dude You could try colder plugs (IK 24's i run) Terry said IK24s are overkill for BPU or less What gap did they have or your coils may be on the way out. Whatever the gap they come with. Those Denso IK plugs are pre-gapped aren't they? Originally posted by Steve Cargill How is your intercooler? Old Originally posted by dude Jake this sounds a bit worrying No shit. get the car to me and i'll check the fueling and put the Det cans on it for a blast. OK mate, we'll sort something out, thanks. WTF are Det Cans? Quote Link to comment Share on other sites More sharing options...
dude Posted May 27, 2004 Share Posted May 27, 2004 The plugs normally are gapped at 30 thou you could close that a nats !!! Dude:flame Dev Det cans let me listen to your engine internals !!!! or the next door neighbours shagging !!! Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 27, 2004 Share Posted May 27, 2004 Jake - buggered/inappropriate plugs will give you a misfire above about a bar of boost or so, and yet the engine will run perfectly under that level. However, a dodgy wire on the SLD will give you intermittent problems whereas the plugs or detonation will happen every time. I'm still erring on the SLD side. Work with me, buddy, this is the cheapest option so far Also, colder air is denser and therefore even harder work for the plugs under boost so the misfire should have got worse (this bit is theory, I've not noticed in real life) But anyway, get to Dude's (don't let him over-rev your car ) and get it checked out for det, fuelling, and a knackered intercooler. -Ian Quote Link to comment Share on other sites More sharing options...
Jake Posted May 28, 2004 Author Share Posted May 28, 2004 Thanks Ian, I'll thoroughly check the SLD this weekend, no chance of getting Dude to look at it anytime soon anyway. What you doing up at this time of night anyway? I thought you forklift drivers needed plenty of rest! Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 28, 2004 Share Posted May 28, 2004 Forklift driver?! Quote Link to comment Share on other sites More sharing options...
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