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Engine trouble
I have got an MY95 WRX and have recently noticed that under hard acceleration when I change gear the car jolts. The only way I can describe it is that it is as if the engine is stalling then restarting mid gear change. The revs drop like they should do during gear change.
This only happens under hard acceleration not whilst around town, I was thinking that it may be caused by a fuel shortage to the engine but Im not sure. The mods I have done are : Full de-cat from the turbo back (HKS Hyper),Have also removed the sensor that was in the old downpipe as it was rusted in.(I think its the lambda)! Uprated panel filter, Bailey dump valve, MY02 WRX TM intercooler conversion. I also have an HKS FCD and a dawes device to fit yet. Any advice would be appreciated. Martin850 |
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Sounds like Fuel Cut to me. - due to overboost.
Stick the FCD on and see if it still happens ;) Do you have a boost guage, or something to monitor the boost with? This would be a good idea, especially if you are thinking of using the dawes. And maybe even a knocklink (although I do now class some kind of knock sensor display on a Scooby as an essential item) |
Highlander, I do have a boost gauge and I think I hit around 0.9 to 1 bar. I do want to get a knocklink but they are pretty pricey.
Still I suppose it is cheaper than a new engine!!!! |
Originally Posted by martin850
Have also removed the sensor that was in the old downpipe as it was rusted in.(I think its the lambda)! Tony:D |
Was I right in thinking that it is the lambda sensor? How much do they sell for as I threw the old one away?
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Originally Posted by martin850
I have got an MY95 WRX and have recently noticed that under hard acceleration when I change gear the car jolts. The only way I can describe it is that it is as if the engine is stalling then restarting mid gear change.
This only happens under hard acceleration not whilst around town, I was thinking that it may be caused by a fuel shortage to the engine but Im not sure. The mods I have done are : Full de-cat from the turbo back (HKS Hyper),Have also removed the sensor that was in the old downpipe as it was rusted in.(I think its the lambda)! Uprated panel filter, Bailey dump valve, MY02 WRX TM intercooler conversion. Are you running an AFR meter and KnockLink, and what fuel do you normally run on? I also have an HKS FCD and a dawes device to fit yet. Any advice would be appreciated With a setup like this, you must be running a boost gauge and a KnockLink, and ideally an AFR meter too. If you are, you need to tell us what these three things are telling you. If you're not, you should fit them ASAP, both for the long-term health of your engine and to assist us in diagnosing the cause of your problem. |
engine trouble
Greasemonkey.I hope this helps you out
Originally Posted by greasemonkey
Is this something that appeared gradually and has been slowly getting worse, or did it just start happening all of a sudden? If the latter, was it tied in to you fitting a new part on the car?
If I remember right it happened all of a sudden. Do you have a boost gauge? Yes I do an I have noticed that it peaks at between 0.9 and 1 bar of boost then settles at around 0.9 What exactly do you mean, that you're running without a lambda sensor at all? What have you done with the hole on the new downpipe, have you blocked it with a spark plug, or have you left it open? I have got an HKS decat down pipe and have blocked the hole with that gasket stuff which hardens when it gets hot. What sort of panel filter? It is a foam filter from japan that I got off ebay. Is this a vent to atmosphere one or a recirculating one? Either way, have you tried refitting the standard dumpvalve to see if the problem goes away? It is a vent to atmosphere one and I had it fitted for around a year with no problems. This will create lower pressure drop across the I/C, allowing an effective increase in boost pressure, as well as delivering a colder, denser charge, which has the effect of leaning your mixture. This is not a happy situation to be in with a Japanese market car unless you are running a KnockLink and AFR meter, along with Optimax and enough octane booster to prevent det. Are you running an AFR meter and KnockLink, and what fuel do you normally run on? I don't have either of these but I always run it on Optimax At this time you want to be leaving these well alone. Given that you've made a number of modifications that, together, affect the engine's breathing in quite a major way, it would appear that there are a number of potential causes for this issue. With a setup like this, you must be running a boost gauge and a KnockLink, and ideally an AFR meter too. If you are, you need to tell us what these three things are telling you. If you're not, you should fit them ASAP, both for the long-term health of your engine and to assist us in diagnosing the cause of your problem. |
If I remember right it happened all of a sudden. Yes I do an I have noticed that it peaks at between 0.9 and 1 bar of boost then settles at around 0.9 I have got an HKS decat down pipe and have blocked the hole with that gasket stuff which hardens when it gets hot. It is a foam filter from japan that I got off ebay. It is a vent to atmosphere one and I had it fitted for around a year with no problems. I don't have either of these but I always run it on Optimax |
I never thought that a knocklink was that important I stand corrected.
[/QUOTE]Not at the same time as one of the mods got installed? Couln't be sure. [/QUOTE]That tends to suggest it's not boost cut then. [/QUOTE]Oh dear, that wasn't really a good move. I doubt it's directly related to this problem, but nevertheless you really need to get that outta there and get a working lambda sensor back in. I am working on that, any idea of prices? [/QUOTE]Hmmm. Does this filter have any sort of oil/mucus on it? Either way if you can't be sure of this filter's providence I'd chuck it and fit one of the ones regularly recommended here (STi, K&N, Green). No Don't think so but will see if I can get hold of a different one to try. [/QUOTE]Either way, you should refit the standard DV and try the car just to rule this out as a cause. Your boost gauge readings mitigate against overboost, so the DV is one of the next most likely suspects, and provided you still have the standard one, an easy suspect to eliminate. I shall have a go tomorrow. That ain't enough on a standard JDM WRX, let alone one with a number of significant induction/exhaust mods. Start using a fair wedge of booster and fit a KnockLink as a matter of urgency.[/QUOTE] Right ok plenty of stuff to buy do you think I should sell the FCD and DAWES? |
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what does a knocklink do?
I've heard this a few times now, but to be honest, I haven't got a clue!! where do you get them? I've got a my96 jap import with s/s exhaust fabricated for the car with HKS vta bov and the ecu has been changed for an STI V2 jobbie(Not my doing) it did have a blitz SUS induction kit, but by talking/listening to numerous people on here or otherwise, they all said to get rid of it and put an ITG panel filter in, but at the mo, it's got the stock air filter in |
What does a Knocklink do?
As far as Im aware it detects noise from the engine block that points to detanation of the fuel and I think that the louder the det then the leaner your fuel to air is. Which is not good.
Im sure someone on here can give a better explanation than me. |
thanks martin850, I understand what you mean, I had a feeling that is what it does, but wanted to make sure.
thanks again Paul S. |
No problems, you should be able to find one for sale on here at some point as I have. I would advise that you get one when you can.
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