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| Scaffy |
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I've been having some dramas with my motor where it seems to be missing. I've all but ruled out the leads and am wondering what else I should be looking at.
It is weird cos it will cruise not too bad, but when I apply light throttle, it hesitates and sometimes backfires then begins to accelerate, and it sounds to be missing and has a noticable loss of power. When I plant my foot from cruising, it will also hesitate, pop and then take off pretty hard. Power loss isn't as noticable at WOT. For a while I've been thinking it's the tune, but when driving down the road the other day, I went over a rough patch and it started driving fine. All the power was back and no more hesitation. That was until I stopped it for a while then started it up again. It was back to s**t. Any ideas?
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| COBRAED |
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{USERNAME} wrote: I've been having some dramas with my motor where it seems to be missing. I've all but ruled out the leads and am wondering what else I should be looking at. Hi Scaffy,
It is weird cos it will cruise not too bad, but when I apply light throttle, it hesitates and sometimes backfires then begins to accelerate, and it sounds to be missing and has a noticable loss of power. When I plant my foot from cruising, it will also hesitate, pop and then take off pretty hard. Power loss isn't as noticable at WOT. For a while I've been thinking it's the tune, but when driving down the road the other day, I went over a rough patch and it started driving fine. All the power was back and no more hesitation. That was until I stopped it for a while then started it up again. It was back to s**t. Any ideas? I'm NO expert, it sounds like you have something loose, maybe have a lok at your ECU? might be a loose connection? that happened to me a couple of weeks ago, and it was my POWERCHIP being loose, ( I pulled my ECU out to put my speaker wires up tru there, just like factory, and i bumpped the chip, not knowing till i started it.) and thats what it was. I don't know if yours would be the same, but thats what mine was!! AND as i said i'm no expert, whats your wires like on your coil? are they tight? Hope this helps!! 
JASON 
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| Scaffy |
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Thanks Jason, I've been definately thinking it could be something loose due to the fact it changed over rough road. I've been thinking about the eec and tweecer connection, but kinda dismissed it. I'll definately check it now.
Today, the first thing I'm going to do is swap the leads out a bank at a time. Yesterday I was changing them one by one and taking it for short drives up and down the carpark. I may have missed it. I think I'm going to have to design a quick-release eec!
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| green car |
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Scaffy, test the resistance of the leads and if one is real high thats the rooted one.
I would more than likely say it will be something loose from what you have said, ignition system maybe. I would go over and check it all.
_________________ 165 Killer Wasps all packaged in a green kmart car, almost an explorer in a way... |
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| Scaffy |
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I've just been out and ruled out the leads. The reason I thought it may have been them is because the other day I went and tightened them all around the boot where it connects to the plug. After that she drove well for a little bit then went back to s**t. I got 4 of my old plugs and swapped the right bank. It made no difference. I swapped the left bank and again it made no difference. The leads are fairly new so I would have been surprised if it was them. I also checked spark in them all and they all gave a pretty strong spark.
I also checked the tweecer connection. I thought it was that to start with. First thing this morning I went for a drive down to the park nearby. It was doing the same s**t as it has been. I parked there, went around and gave the tweecer a jiggle then started it up again. When I took off it was running back to normal... for about 500m, then it went back to s**t. I hit all the contacts between the tweecer and eec with a heap of contact cleaner and made sure there was no gunk on any of them. This made no difference. Next I'm going to switch the eec out, then I'm going to chuck my original coil on and see if that's not the problem. One more thing I think I noticed today, is that some of the popping might be coming from the airbox
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| s-tranzor |
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out of curiosity Scaffy, what conditions are you planting it under? IE, what gear, speed before plant and RPM... Also, does it ping during hill climbs when/or if it's running a bit hot?
reason I ask is mine used to do same thing. After I replaced O2 sensors and took it back to BPT for a dynotune (last tuesday) it was fine. Apparently it was running too lean due to bad sensors. He was able to richen the AFR which gave more torque and better idle when hot... runs cooler now too. |
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| EBXR8380 |
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Clean maf..
If its backfireing when opening throttle ?? Its usually a lean condition.. Check fuel pressure, fuel filter and pump.. Check fuel reg and hose to it... Check inlet and coolant temp sensors.. Check for inlet leaks between maf and engine.. Check PCV is pluged in properly.. Check condition of cats.. If plugs, leads, rotor and cap havn't been changed recently ?? I would change them.. The high voltage connection on these coils can corrode and cause high resistant connection to dissy lead... Check all battery connections inclusing body to engine...
_________________ As in ZOOM 126 edition |
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| green car |
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Has anyone had a trouble free run with a bpt tuned/modified car?
_________________ 165 Killer Wasps all packaged in a green kmart car, almost an explorer in a way... |
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| Timmeh |
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I had those exact symptoms and it was a lead. It was burnt and cracked through cause it was on the headers.
Hesitates then goes but at full throttle it went limp then took off but with less power. Lead my be split through and somtimes makes contact hence the time you said it had power back after a bump in the road. I'd take each one off and have a good look at them. |
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| Scaffy |
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Yeah, I ruled out te leads as I'd changed all one side and drove with the same result, then swapped the other 4 out with the same result.
I think I may have found the culprit. EBXR8380, you've mentioned it. It may be the ECT sensor as I'd suspected before. I hadn't programmed the datalogger for it correctly (and still may not have) but at the moment it's stuck around 50*F. The IAT sensor is programmed the same and is reading around 100*F. Before, I was just reading volts which I don't think was right. So, regardless if I've got them programmed spot on, I shouldn't be seeing a lower coolent temp than inlet air. Now to go find one and see what happens.
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| Scaffy |
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{USERNAME} wrote: out of curiosity Scaffy, what conditions are you planting it under? IE, what gear, speed before plant and RPM... Also, does it ping during hill climbs when/or if it's running a bit hot?
reason I ask is mine used to do same thing. After I replaced O2 sensors and took it back to BPT for a dynotune (last tuesday) it was fine. Apparently it was running too lean due to bad sensors. He was able to richen the AFR which gave more torque and better idle when hot... runs cooler now too. It's not so much when I plant it. It's more a case of when I ease the throttle on it leans out to around 16-18:1 and backfires, pops and shudders until I give it a bit more then it richens up, snaps out of it, then away she goes. I replaced o2 sensors only about 5 or 6 months ago. It happens at any speed and any rpm when at cruise. I can be doing 100 on the freeway and ease throttle on in 5th or 4th and I get the same thing. When in 3rd doing 40kmh it'll do it and in 2nd it will do it. There's no pinging either. It's like it is in the tune, where in closed loop it needs more fuel on very light throttle and when you open it up to WOT, open loop takes over and it goes hard again. The only problem is that if it were the tune, it wouldn't trip out and go back to normal for a short time then go back to s**t.
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| Scaffy |
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{USERNAME} wrote: Clean maf..
If its backfireing when opening throttle ?? Its usually a lean condition.. Check fuel pressure, fuel filter and pump.. Check fuel reg and hose to it... Check inlet and coolant temp sensors.. Check for inlet leaks between maf and engine.. Check PCV is pluged in properly.. Check condition of cats.. If plugs, leads, rotor and cap havn't been changed recently ?? I would change them.. The high voltage connection on these coils can corrode and cause high resistant connection to dissy lead... Check all battery connections inclusing body to engine... MAF has been cleaned and appears to be running fine on the datalogger. Fuel pressure has been set to 39lb without vacuum. Can anyone tell me what this should show with vacuum? I upped it to 44lb, then 49lb to see if extra pressure made a difference and there was no noticable difference in it's behaviour. Fuel filter and fuel pump, I'm yet to check. Can someone tell me where the relay is for the fuel pump? Fuel pressure reg is an adjustable jobby, as mentioned above pressure set to 39lb. I'm wondering if it's possible that there could be a problem with the vacuum line on the afpr? I don't know much about it but it's just a though. Inlet and coolant temp sensors are both good. I thought ect sensor was buggered but it turns out that I had programmed it wrong in the datalogger again! What's PCV? Cats are fairly new, but you never know. They'll be hard to check though, as they're welded to the headers. Also, what do I check for when looking at the condition of the rotor and cap? I had a look at the rotor and it looks a bit rough around the edge that connects with the cap. Is this normal? This is really, really getting frustrating. I kinda need this thing to be running properly before Wednesday or Thursday next week when I go back to work. It's wasting all my bloody time off.
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| green car |
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Have you spoken to your tuner about it, maybe he can shed some light.
_________________ 165 Killer Wasps all packaged in a green kmart car, almost an explorer in a way... |
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| Scaffy |
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for my own reasons, I don't wanna be speaking to them
_________________ Trickflow Street Heat top end kit, 70mm BBK TB & EGR, 24lb injectors, Underdrives & 3.73s: 275rwhp - 13.15@105mph NA / 12.37@116mph N20 |
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| XH5LWEPN |
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Im going to be very interested in what the cause of this is as my mate is having exactly the same problem. Also tuned at same place as yours.
_________________ STREETBUILT RACING |
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