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Jun 11, 2011 21:27:27 GMT
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Heres a strange one. Car is a 1990 Polo 1.3 CL, recently converted it from single point injection to multipoint using GT head, cam, injection system, ECU and wiring. Cant get the motor to fire off the key, getting a spark, getting fuel, tried changing the Lambda, temp sensor, Dizzy, cap, leads, fitted the GT fuel pump (priming when ignition on), cleaned out the throttle body, tried the AFM off my other GT motor, no joy, motor will turn over till the battery goes flat. BUT, If I spray Easystart into the intake motor will fire and idle fine  Did notice though, whan the motor does fire it idles at 800 rpm, I.e not in cold start mode (my other GT runs at 1500 for a minute or so), also if I leave the motor idling till it's warm, switch it off it still wont fire up again without the Easystart. |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold  86 Mk4 Escort RWD V8, sold |
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Jun 11, 2011 21:41:21 GMT
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Sounds like low compression or incorrect ignition timing to me - they will make it a complete pain to start.
Camshaft timing, ignition timing, valve clearances?
Have you tried driving it? I'm going to guess that it is either massively slow or pinks like crazy - or both.
Also, have you tried applying throttle when turning it over? If the cold start air valve (is it a bypass valve or a throttle-opening-stepper motor on these?) isn't working it might not allow enough air through to start the engine, but a little (or maybe a lot of) throttle might help.
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Jun 11, 2011 22:00:40 GMT
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Have'nt done a compression test but felt healthy when turning it over by hand, will do a compression test tomorrow, cam timing is ok, could be ignition timing as sometimes when turning it over motor will turn slow then fast (need to dig out my timing gun), hydraulic tappets so valve clearances will be ok.
Have'nt tried driving it yet.
Tried throttle when turning it over but no effect, guessing it's a bypass valve as no stepper motor on the TB, the bypass valve works in the AFM right ?
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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Jun 11, 2011 22:32:21 GMT
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Have'nt done a compression test but felt healthy when turning it over by hand, will do a compression test tomorrow, cam timing is ok, could be ignition timing as sometimes when turning it over motor will turn slow then fast (need to dig out my timing gun), hydraulic tappets so valve clearances will be ok. Have'nt tried driving it yet. Tried throttle when turning it over but no effect, guessing it's a bypass valve as no stepper motor on the TB, the bypass valve works in the AFM right ? Bypass valve will be between the maifold and the atmosphere - across the throttle flap. Might be worth double-checking the cam timing? I know from experience that I's easy to get it a tooth out. Does the ECU need a 'cranking' signal so that it knows to add a bit more fuel? If so is it connected? Best of luck! |
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murran
Part of things
Posts: 610
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the fuel pump maybe working but, are the injectors switching while cranking? sounds like thats your problem, cus once you come off the key it runs just fine... I'm betting you can easily bump start it too?
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the fuel pump maybe working but, are the injectors switching while cranking? sounds like thats your problem, cus once you come off the key it runs just fine... I'm betting you can easily bump start it too? Not tried bump starting but you are probably right. How do I check if the injectors are working during cranking ?, what would control the injectors during cranking ?, ignition feed ?, ECU ?, relay ? Would certainly explain why the motors not firing hot or cold and the squirt of Easystart works. |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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murran
Part of things
Posts: 610
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Jun 12, 2011 11:12:31 GMT
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if you have an ossiscope, you could hook that up to the switched side (earth) of the injectors.
and check youve got the ignition live on the other wire, both with ignition on and while cranking.
or probably more simply... if you can pull the fuel rail out leaving the injectors on the rail and all plugged in, then move it so you can see fuel spraying out (not in your face that is).
get an able assistant to crank it over and you look? oh and don't smoke while looking lol!
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Jun 12, 2011 11:17:30 GMT
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if you have an ossiscope, you could hook that up to the switched side (earth) of the injectors. and check youve got the ignition live on the other wire, both with ignition on and while cranking. or probably more simply... if you can pull the fuel rail out leaving the injectors on the rail and all plugged in, then move it so you can see fuel spraying out (not in your face that is). get an able assistant to crank it over and you look? oh and don't smoke while looking lol! Worth a shot. Best bet if you do this would be to only plug in one of the injectors and point it into a bottle, you don't want to be spraying atomised fuel all over your alternator or starter while cranking. Edit, when I say only plug in 1, I mean plug 1 into the wiring loom, you'll need all 4 in the rail obviously! |
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Last Edit: Jun 12, 2011 11:18:25 GMT by RobinJI
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murran
Part of things
Posts: 610
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Jun 12, 2011 11:24:46 GMT
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as for why......
to work out what controls this youd have to look at the wiring diagrams for both cars. I'm guessing theres a difference in the wiring between the single point fusebox and dash loom and the multi point engine loom and ecu.
are there any earth's into the engine loom youve not attached?
check the injectors are working (or not) before getting into the "whys".
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bortaf
Posted a lot
Posts: 4,549
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Jun 12, 2011 13:42:37 GMT
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does it start ok with a push start ? if it does check for an ign live at the coil after trying with the key, if the live dissapears after cranking it's the ign switch, happens a fair bit on golfs not had a polo with it though ?? what happens is the ign switch on the back of the sterring lock burnes out and you loose the live whilst cranking and after, switch the ign off and back on and it returns to only go again when you crank the engine ? just a possability if all else fails, this one confused 3 AA men and me for a while  |
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Last Edit: Jun 12, 2011 13:46:05 GMT by bortaf
R.I.P photobucket
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Jun 12, 2011 15:06:33 GMT
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as for why...... to work out what controls this youd have to look at the wiring diagrams for both cars. I'm guessing theres a difference in the wiring between the single point fusebox and dash loom and the multi point engine loom and ecu. are there any earth's into the engine loom youve not attached? check the injectors are working (or not) before getting into the "whys". Man am i an Idiot, found an extra earth wire in the bulkhead down the front of the battery  Working fine now  Yeah Murran, had to change the engine bay loom, GT loom and fusebox plugs into the dash loom at the bulkhead Here's a pic   Cheers for the help guys , now that its running i can deal with the important stuff like alloys and lowering ;D  |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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murran
Part of things
Posts: 610
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Jun 12, 2011 23:16:18 GMT
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did you do the injector cranking thing? was it that?
glad its sorted anyway dude!
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did you do the injector cranking thing? was it that? glad its sorted anyway dude! Na, did'nt get that far, re-fitted the TB i'd cleaned for the umpteenth time, thought id run an earth straight from the motor to the battery and thats when i found the extra earth wire, two thin ones spliced together going into the loom. Well pleased it's running now, MOJO is restored, better than last weekend when i could have torched it |
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold 86 Mk4 Escort RWD V8, sold |
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