Snowman Posted December 4, 2002 Share Posted December 4, 2002 Hi I haven't posted in the Technical section before as I'm not a technical person at all! sorry! I've recently had my J spec TT auto decatted, fantastic acceleration increase but beyond about 5,500 rpm on hard acceleration I get a sudden jolt and the engine light comes on then about 10 seconds later goes out. Normal driving its not a problem its just if I am gunning it a bit, overtaking etc that it cuts and jolts. I'm going to the rollign road event in Aylesbury on Saturday and just a bit concerned if this is something serious or it jolts heavily while on the rollers. Any help is grately appreciated. Link to comment Share on other sites More sharing options...
Gaz Walker Posted December 4, 2002 Share Posted December 4, 2002 Sounds like you hitting fuel cut... Have you got an Fuel Cut Defender of similar in use? Gaz. Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 Hi Gaz That was one of the things I had thought but then didn't think any more about it as I had a defender fittd at the time. could it be that there is some problem with that? Link to comment Share on other sites More sharing options...
Terminator Posted December 4, 2002 Share Posted December 4, 2002 You may have hit the new limit some are adjustable, Which on do you have? How was it fitted solder or the dreaded scotch locks? Do you have a boost gauge? If not I suggest you get one so that you can see what boost level causes this to occur. Be careful until you have it sorted. Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 I don't have a boost gauge but I know after the decat was fitted it was running about 1.2 In terms of the fitting I don't know but will check with the place that fitted it today. Do you think this is the most likely cause then? Link to comment Share on other sites More sharing options...
Gaz Walker Posted December 4, 2002 Share Posted December 4, 2002 Snowman, If you have a TRL FCD, they only RAISE the fuel cut to 19psi. So now you may be hitting that. Probably due to the nice cold air we've got now... Gaz. Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 I see. What would you recommend to get round this then? I can see the wallet opening again and another chunk of money disappearing!!! Link to comment Share on other sites More sharing options...
Druid Posted December 4, 2002 Share Posted December 4, 2002 One option is to fit a restrictor plate, I've seen posts about it appearing off and on. Link to comment Share on other sites More sharing options...
Patrick_Devlin Posted December 4, 2002 Share Posted December 4, 2002 Snowman, I get that with mine. I havent had the FCD fitted yet and dont know what boost I'm running. From what I've read on this BBS it looks like you're hitting fuel cut. If the problem persists with the FCD fitted then you need a restrictor ring fitted. Chris Wilson does one for the JSpec. I should be up at the meet on Saturday. Not going to the rolling road event, but will pop along afterwards. See you there Pat Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 Hi Patrick How are you doing. Will see you on Saturday pm then. At least I don't feel alone experiencing this problem then! Link to comment Share on other sites More sharing options...
Patrick_Devlin Posted December 4, 2002 Share Posted December 4, 2002 I was gunning it down the M40 from Birmingham last night (got to get away from that place fast!!!) and decided to nail it even more. At about 4500rpm and not even at full throttle the cut came on. I it only happens above 135 leptons... Link to comment Share on other sites More sharing options...
Andrew Posted December 4, 2002 Share Posted December 4, 2002 What fuel are you running snowman? Does the engine light come on everytime it happens? Or do you sometimes just get a bang/jolt? You could also be suffering from "knock", higher octane fuel and booster will sort that out. Happens to mine if I run normal fuels. I have the opposite problem to you, but that's in a different thread Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 Hi Andrew I always run Optimax without exception and have done for the past 3 months. Every time I get the jolt I get the engine light! but only when running it hard. Link to comment Share on other sites More sharing options...
Andrew Posted December 4, 2002 Share Posted December 4, 2002 Ah you run the same as me then, I often use Optimax without millers booster and don't suffer knock. As for the fuel cut, I have only ever hit that once and it scared the living shite out of me. I'd only had the car a couple months and thought "Oh f*** I've broken it!" Like you I do not own a boost gauge, so will get one asap to see what boost I'm running. If you read my post about FCD, I have searched to see if the previous owner had one fitted, so far I haven't found any evidence of one. So this leads me to believe these decat J-specs must hit a wide range of boost, because I hit fuel cut once but haven't since. Link to comment Share on other sites More sharing options...
Terminator Posted December 4, 2002 Share Posted December 4, 2002 It definitely sounds like higher level fuel cut, not a good thing. Stay off the high boost until you can see what’s going on with a boost gauge. A restrictor ring may be the solution but you really need to know what boost you are running before you can accurately diagnose the problem. The fuel mixture is likely to be lean and your cylinder temps are likely to be high. I think Matt H recorded 1050 degrees, 950 is a good setting for a warning. Before fitting my restrictor ring I was hitting 1.4 bar which is a bit too high. If you are running higher than stock boost a boost gauge is and essential bit of kit IMHO Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 Hi Terminator Thanks for the info. i have just spoken to Leon and he recommended keeping off the power unit I can get it up to him. I will def be getting a gauge now. Leon also said not a good idea at all to run it on the rolling road until this is sorted so will ahve to pull out of Saturday's at Aylesbury, but will be there to see how everyone else gets on. Link to comment Share on other sites More sharing options...
Dragonball Posted December 4, 2002 Share Posted December 4, 2002 Originally posted by Snowman Hi Terminator Thanks for the info. i have just spoken to Leon and he recommended keeping off the power unit I can get it up to him. I will def be getting a gauge now. Leon also said not a good idea at all to run it on the rolling road until this is sorted so will ahve to pull out of Saturday's at Aylesbury, but will be there to see how everyone else gets on. Very good advice m8 - I hit fuel cut a couple of times when setting up the SBC - scary stuff! The other day experienced a loss in power under heavy acceleration - but no engine light - think this was the SBC boost cut and warning coming in at 1.15Bar gad this cold air make the machine go like stink! Paul:cool: Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 I guess the new question is which boost gauge to get! Family will have to wait for Christmas presents I need to by myself and gauge! Link to comment Share on other sites More sharing options...
Dragonball Posted December 4, 2002 Share Posted December 4, 2002 You have pm Link to comment Share on other sites More sharing options...
MONKEYmark Posted December 4, 2002 Share Posted December 4, 2002 when i used to get fuel cut it was under hard driving or when i did kick down in the auto have had it at 80mph too.if you build speed up normal it dont do fuel cut.scary when it first happens to you.i have since fitted a trl fuel cut and it has be ok. apart from cold mornings on way to work used to boot it and it felt like i was hitting the second fuel cut limit of 19psi i think thats what its second limit is. try get a boost gauge and egt gauge to keep an eye on things dont know if water injection and a big fmic will help at all.i hope it does.i have both cw decat pipes in and have hit a high of 1.4bar will seek advice on what else can be done. best to keep off rollers till its running ok,thats why i dont fancy putting on rollers. Link to comment Share on other sites More sharing options...
Snowman Posted December 4, 2002 Author Share Posted December 4, 2002 Hi Mark Cheers. I am looking at Gauges at the moment, probably something I can mount in the clock space. I like the Greddy 52mm with green light on a black bezel if anyone has one? Link to comment Share on other sites More sharing options...
Terminator Posted December 4, 2002 Share Posted December 4, 2002 If Santa is buying, go 60mm and get an EGT and pillar pod mount aswell. Link to comment Share on other sites More sharing options...
MONKEYmark Posted December 4, 2002 Share Posted December 4, 2002 Originally posted by Snowman Hi Mark Cheers. I am looking at Gauges at the moment, probably something I can mount in the clock space. I like the Greddy 52mm with green light on a black bezel if anyone has one? i put 60mm boostgauge in left big air vent and egt in right hand big air vent after seeing eyefi`s install.look good there but would look a lot better in an apillar pod 60mm boost gauge in dashboard air vent Link to comment Share on other sites More sharing options...
Billy Posted December 5, 2002 Share Posted December 5, 2002 grandprix racewear do a 52 mm combined spa design duel boost pressure and egt gauge for £252.21 it does psi or bar temp in f or c is back lit in red or green has warning lights and outputs and a max value memory and as it is 52.mm it will fit straight in the standard clock hole ther web site is http://www.grandprixracewear.com or phone 08701 600 950 i do a bit of 125cc gearbox kart racing and i get quite a bit of kit from them im out testing my mates new 250.cc kart this weekend if like me you think the sup is quick of the line have a go in a gearbox race kart 0 to 60 = 2.5 sec Link to comment Share on other sites More sharing options...
Snowman Posted December 5, 2002 Author Share Posted December 5, 2002 Quality, Thanks for the advice. Will check this out and hopefully some of the guys going to the meet on Saturday will have gauges that I can have a look at. Link to comment Share on other sites More sharing options...
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