AlexM Posted May 2, 2009 Share Posted May 2, 2009 I've just taken my NA 5Spd out for a run, and it's not right at all. The power is very hesitant past 4krpm, if it comes at all, and when it does come it can feel very lumpy. It also feels rough at idle, possibly like a misfire? I took it for a run last weekend and it was fine, and since it's just sat on the drive. I'm doing a sprint event tomorrow.. What can I look for and what can I test? Help! Quote Link to comment Share on other sites More sharing options...
jaymdee Posted May 2, 2009 Share Posted May 2, 2009 Hi Alex, best guess is plugs, dizzy cap, leads ? Is there a diagnostic post on the NA to check for error codes Quote Link to comment Share on other sites More sharing options...
bignum Posted May 2, 2009 Share Posted May 2, 2009 As john said possible lead/plug failure, an easy way to find which 1 is.... get the car running wear some rubber gloves/marigolds then pull each lead off 1 at a time, the engine note should change ie worse when you pull a good 1 off,put that 1 back on, if you pull 1 off and theres no change thats the bad 1, then swap stuff off your other car to check the fault, good luck. Quote Link to comment Share on other sites More sharing options...
AlexM Posted May 5, 2009 Author Share Posted May 5, 2009 I was a bit tired to take a look at this, so only had a play today. The car runs perfectly when cold, idles nicely, seemed to take off ok. It starts playing up when it's warmed up, and going back to idle shows a very slight misfire (engine sounds fine, I can only hear it from the exhaust) - disconnecting a spark plug produced a much more prounced misfire and a less healthy sounding engine (I tried them all, but each caused a completely different effect to when they're all connected). I did the ecu diagnostic, by shorting the pins and checking for an error code - there were none stored. Is there something else I should be looking at here? I would think the difference between hot/cold running would rule out the Distributor and sparks (and I would have thought that'd produce an error code)? Quote Link to comment Share on other sites More sharing options...
legendswraith Posted May 6, 2009 Share Posted May 6, 2009 What kind of shape is the MAF in? also if you have a strut brace on the car have you crushed the vacuum lines coming off the top of the throttle body? Have a look around the vacuum lines anyway especially the one on top of the throttle body, when that split on my GS300 it ran rough as a bears bum. Quote Link to comment Share on other sites More sharing options...
AlexM Posted May 6, 2009 Author Share Posted May 6, 2009 What kind of shape is the MAF in? also if you have a strut brace on the car have you crushed the vacuum lines coming off the top of the throttle body? Have a look around the vacuum lines anyway especially the one on top of the throttle body, when that split on my GS300 it ran rough as a bears bum. It's a non turbo, so I don't think any of that applies? Thanks though. Quote Link to comment Share on other sites More sharing options...
SteveR Posted May 6, 2009 Share Posted May 6, 2009 My money is on the distributor/associated wiring being on its way out. Quote Link to comment Share on other sites More sharing options...
AlexM Posted May 6, 2009 Author Share Posted May 6, 2009 My money is on the distributor/associated wiring being on its way out. How much money? Quote Link to comment Share on other sites More sharing options...
SteveR Posted May 6, 2009 Share Posted May 6, 2009 How much money? 10p, it's all I have! Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 6, 2009 Share Posted May 6, 2009 I was a bit tired to take a look at this, so only had a play today. Not sure how that gels with the "Urgent!" you put on the thread then The car runs perfectly when cold, idles nicely, seemed to take off ok. It starts playing up when it's warmed up, and going back to idle shows a very slight misfire (engine sounds fine, I can only hear it from the exhaust) If it struggles catching the warm idle and pops on overrun it could be overfuelling. Check/clean O2 sensors. -Ian Quote Link to comment Share on other sites More sharing options...
legendswraith Posted May 6, 2009 Share Posted May 6, 2009 It's a non turbo, so I don't think any of that applies? Thanks though. The GS300 uses the 2jz-ge so they should be identical if its the non vvti version Quote Link to comment Share on other sites More sharing options...
AlexM Posted May 6, 2009 Author Share Posted May 6, 2009 I will try changing the dizzy, plug cables, and cleaning the O2 sensors (and possibly gaining or losing a mighty ten pence in the process!). legendswraith do you mean the sensor that's behind the air filter by MAF or something else? I searched on here and apparently the NA has no MAF (I'm not entirely sure what one is). I'm not sure which the vacuum lines are either, but I haven't searched for those yet! Not sure how that gels with the "Urgent!" you put on the thread then No need for the sarcasm Ian. I didn't get home until 9pm on Saturday (misfire appeared when I was out) and pulling my other car apart to test that late in the evening when I was doing a sprint the next morning didn't appeal. Luckily Bazza (one of the organisers of the Toyota Sprint Series) gave me the OK to run my daily, so I took the relaxed option and did that - and got some sleep instead (5am start!). You may if you wish remove the 'Urgent', since it is no longer so. Quote Link to comment Share on other sites More sharing options...
legendswraith Posted May 6, 2009 Share Posted May 6, 2009 The MAF sensor is the black lump that has wires and a plug going to it and its on the metal flange/pipe that comes from the airbox, or if you have a later version its on the black connector that looks like a bit of drainpipe. The vacuum lines are fairly apparent you will be able to see them in the middle of the engine roughly in line with the topmounts Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 6, 2009 Share Posted May 6, 2009 No need for the sarcasm Ian. I didn't get home until 9pm on Saturday (misfire appeared when I was out) and pulling my other car apart to test that late in the evening when I was doing a sprint the next morning didn't appeal. Luckily Bazza (one of the organisers of the Toyota Sprint Series) gave me the OK to run my daily, so I took the relaxed option and did that - and got some sleep instead (5am start!). You may if you wish remove the 'Urgent', since it is no longer so. I should have read all that into "I was a bit tired to take a look at this", my bad Actually if it splutters on WOT, it's not the O2 sensors as it'll be out of closed loop, and it's not a vac leak to a MAP (if you have one), as it'll run *better* under acceleration compared to a terrible idle. Probably ignition, then - but funny it should happen suddenly rather than it gradually getting worse. HT lead maybe? Could be the MAF if it's tired and reading the wrong values, a multimeter might help there - it'll be underfuelling. Checking the mix on a dyno is hassle and expensive but can tell a lot (unless you have a wideband handy). -Ian Quote Link to comment Share on other sites More sharing options...
Digsy Posted May 6, 2009 Share Posted May 6, 2009 I'm trying to diagnose a misfire on my girfriend's car at the moment and its a right pain. If its ok at idle and steady state then I reckon you can be pretty certain that the MAT, MAP, O2, cam and crank sensors are OK, as they are all required for steady state closed loop fueling and spark. If it only occurs under accelaration then it could be the throttle postion sensor, which you should be able to check out with a multimeter, or a loss of fuel pressure control. If you suspect its over fuelling then it could be a knackered fuel pressure regulator or FPR vac hose. If its under fuelling it could be the FPR, hose, fuel filter or pump, blocked injectors, etc. If you can rule all of that out and it appears to be overfuelling because in fact it is misfiring and chucking raw fuel down the exhaust, then start to look at your ignition system. One other item to mention is the coolant temperature sensor, as the ECU may initially use this to decide when the engine has warmed up. This is the problem solving route I'm trying to take anyway, starting with the cheapest components and whatever I can check with a mulitmeter. One other thing to check (from your original post) is the operation of the variable intake manifold valve, as that should come in at about 4k RPM. I'm not sure whether the ECU has the fuelling hard-coded into it for when this valve operates. If so then maybe if it doesn't work it will screw up the AFR north of 4k. Quote Link to comment Share on other sites More sharing options...
Guest drlee Posted May 8, 2009 Share Posted May 8, 2009 if missing on load,usually shorting leads or crap plugs,the na supe sounds like the fuel pumps about to elope,similar symptoms,worlds apart.im not stupid.just trying to be helpfull. d Quote Link to comment Share on other sites More sharing options...
AlexM Posted May 15, 2009 Author Share Posted May 15, 2009 Well, I did what I could to test it, then took it to Silverstone garage. Cylinder 5 seems to be holding about half the pressure of the rest, which I take to mean the engine might as well be written off. Thanks for the advice given. I'm really not sure what to do with this car now.. Quote Link to comment Share on other sites More sharing options...
little num Posted May 15, 2009 Share Posted May 15, 2009 change the engine mate its easy as, i will do it for a good price. Quote Link to comment Share on other sites More sharing options...
SteveR Posted May 19, 2009 Share Posted May 19, 2009 Well, I did what I could to test it, then took it to Silverstone garage. Cylinder 5 seems to be holding about half the pressure of the rest, which I take to mean the engine might as well be written off. Thanks for the advice given. I'm really not sure what to do with this car now.. Doh! I owe you 10p, give that to James to get a new engine fitted. Speak to Konrad too, he seems to be absorbing quite a few Supras recently so might have access to spares or know someone who could help. Quote Link to comment Share on other sites More sharing options...
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