Fizzy T Posted October 21, 2015 Share Posted October 21, 2015 Alright guys, I own a 96 UK Spec TT Auto running BPU mods and for as long as I remember I've thought it had an intermittent misfire. It starts perfectly fine but after pulling off the drive and leaving my small cul de sac you can actively notice the revs dropping out every 3 seconds or so by say 100-200rpms, they just dip then come back instantly. Makes me think a cylinder isn't firing and it's struggling, I've not taken it past 20-30mph since it's got worse this week and it's almost always worse when it's cold out. I'm quite mechanically minded so I've already swapped out all the coilpacks and the ignitor and the problem persists, I then checked my plugs were actually sparking properly and it seems they're fine. I'm going to change the plugs soon anyway just in case it's a blow out issue. I have performed a compression test twice on each bore and the results were good by the looks of it... Using a long screwdriver I listened to the injectors while it was idling and as far as I can tell they're all happily ticking away squirting in the good stuff so I don't think it's a dodgy injector but I could be wrong, I'll happily be wrong if I could just find out what's wrong. The oil and filter has all been changed but that was sure not going to fix it, the only thing left to change is the spark plugs incase a spark is blowing out on idle / low revs Quote Link to comment Share on other sites More sharing options...
Fizzy T Posted October 21, 2015 Author Share Posted October 21, 2015 Also worth noting I have inspected the coil pack clips and tried different coil pack sets on each one and they all still generate a spark to the plug, the clips themselves look in good condition and aren't broken in any way. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 21, 2015 Share Posted October 21, 2015 It wont be a spark issue, at least not of the blow out variety, that would only happen at full boost anyway, I would suspect a idle control issue, but your saying that it does it under load as well? are you sure the coil pack connectors are making proper contact as this can cause these symptoms. I would also presume you have checked the ignition timing as well? and is the fuel pressure correct? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 22, 2015 Share Posted October 22, 2015 Without diagnostics it's a lottery, but if I had to make a stab at it I would suggest you RENEW all the connector terminals to the coil packs. Toyota sell repair kits, the terminal ready crimped to a short length of insulated wire. Either solder and heat shrink insulate the connections, or use proper Raychem internal hot melt glue, shrinkable crimp connectors. If the plastic terminal shells are iffy renew them, too. the wires to the coil packs are polarity conscious, make sure they are all right, both now, and after doing the terminal changes! Quote Link to comment Share on other sites More sharing options...
Big Supes Posted October 22, 2015 Share Posted October 22, 2015 Any error codes? Sounds like its hunting when it comes off cold start. I'd would check the IACV. Quote Link to comment Share on other sites More sharing options...
Fizzy T Posted October 22, 2015 Author Share Posted October 22, 2015 I know sparks should only blow out on boost but I'm at wits end and grabbing at straws now, so many people keep saying coil pack clips so I guess it's time to just bloody do it...if it still does it least I know I've got new clips on there. I cleaned out the idle control valve a month or two ago even though it was actually really clean inside. No idea about the fuel pressure and no warning lights are popping up on the dash so I gather there's not a fault code. I don't own a reader Quote Link to comment Share on other sites More sharing options...
Fizzy T Posted October 22, 2015 Author Share Posted October 22, 2015 I'll double check the timing too, that's one thing I've not checked in a while. The revs do dip when higher in the range but not when on boost...that or you can't feel it. Quote Link to comment Share on other sites More sharing options...
Big Supes Posted October 22, 2015 Share Posted October 22, 2015 Smelling rich on idle? Quote Link to comment Share on other sites More sharing options...
Fizzy T Posted October 23, 2015 Author Share Posted October 23, 2015 Always has done. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted October 23, 2015 Share Posted October 23, 2015 Always has done. In that case I would check the lambda and ECU coolant temp sensors, as they will both cause a default rich mixture. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.