need help
05-01-2007, 10:52 PM
#1
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Join Date: Apr 2005
Posts: 8
me and a buddy have been working on his 86 rx7 ...
it WAS a GTU, but it now has full T2 drivetrain minus the engine and ECU/wiring harness.
when the car last ran it had the stock motor in it, and it badly blew a coolant seal and the motor went shortly after that... so we followed the haynes manual and rebuilt a T2 engine we picked up from a buddy with all new seals and whatnot... wasn't too bad...
here's a few mods that have been done to the setup... the rebuilt engine has a Racing Beat header on it, straight thru exhaust with no cat/silencer. it is a 4-port engine (turbo) with n/a rotors. we got porting templates from atkins.. the intake was bridge ported and the exhaust was race ported.
the engine's OMP was disabled and unhooked, and we're running a synthetic 2-stroke oil 40:1 premix in the fuel tank.
and here's where the problems start.
now, minus us not having the throttle cable hooked up, that shouldn't keep the engine from starting. short of hooking up a compression gauge up to the motor and checking it, by my ear, the motor has very good even compression with good loud thumps coming out the tailpipe. i had heard from a friend to put a small amount of atf fluid into the trailing hole of each rotor housing just to help with the last little bit of compression, since the motor has yet to run. we bought brand new spark plugs and the wires are hooked correctly to the according coilpacks and we have a good hot spark, we are getting PLENTY of fuel... you can smell it if you crank the car for more than 5-10 seconds.
but you can crank and crank and crank it, and it never even tries to start, not even so much as a sputter. i'm very confused.
now i know the n/a engines were 6 port. the motor we put together is a 4-port with according intake manifold, and the n/a air meter, plus the emissions delete kit (can't remember where he ordered it from) which basically consists of a few block-off plates, and us plugging extra vaccuum hoses.
i'm not exactly sure if we're using the right ECU, or what the deal is.... i'd have to pull the carpet back and check the number on it, because i know mazda used several different variations in that car....
is it not starting because it was incorrectly ported ? did we time it wrong ? we followed the instructions EXACTLY as the book stated and it went together all too smooth.
so we're stuck between a rock and a hard place trying to figure out why this thing won't even attempt to start.
i'm dying to hear this ported 13b scream down the road with the RB header and straight exhaust.
ANY HELP WOULD BE GREATLY APPRECIEATED!!!
thanks
Jacob
it WAS a GTU, but it now has full T2 drivetrain minus the engine and ECU/wiring harness.
when the car last ran it had the stock motor in it, and it badly blew a coolant seal and the motor went shortly after that... so we followed the haynes manual and rebuilt a T2 engine we picked up from a buddy with all new seals and whatnot... wasn't too bad...
here's a few mods that have been done to the setup... the rebuilt engine has a Racing Beat header on it, straight thru exhaust with no cat/silencer. it is a 4-port engine (turbo) with n/a rotors. we got porting templates from atkins.. the intake was bridge ported and the exhaust was race ported.
the engine's OMP was disabled and unhooked, and we're running a synthetic 2-stroke oil 40:1 premix in the fuel tank.
and here's where the problems start.
now, minus us not having the throttle cable hooked up, that shouldn't keep the engine from starting. short of hooking up a compression gauge up to the motor and checking it, by my ear, the motor has very good even compression with good loud thumps coming out the tailpipe. i had heard from a friend to put a small amount of atf fluid into the trailing hole of each rotor housing just to help with the last little bit of compression, since the motor has yet to run. we bought brand new spark plugs and the wires are hooked correctly to the according coilpacks and we have a good hot spark, we are getting PLENTY of fuel... you can smell it if you crank the car for more than 5-10 seconds.
but you can crank and crank and crank it, and it never even tries to start, not even so much as a sputter. i'm very confused.
now i know the n/a engines were 6 port. the motor we put together is a 4-port with according intake manifold, and the n/a air meter, plus the emissions delete kit (can't remember where he ordered it from) which basically consists of a few block-off plates, and us plugging extra vaccuum hoses.
i'm not exactly sure if we're using the right ECU, or what the deal is.... i'd have to pull the carpet back and check the number on it, because i know mazda used several different variations in that car....
is it not starting because it was incorrectly ported ? did we time it wrong ? we followed the instructions EXACTLY as the book stated and it went together all too smooth.
so we're stuck between a rock and a hard place trying to figure out why this thing won't even attempt to start.
i'm dying to hear this ported 13b scream down the road with the RB header and straight exhaust.
ANY HELP WOULD BE GREATLY APPRECIEATED!!!
thanks
Jacob
05-02-2007, 12:18 PM
#4
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Join Date: Apr 2005
Posts: 8
Originally Posted by Leetheslacker' post='870178' date='May 1 2007, 11:14 PM
if you can smell the fuel that bad, it might be flooding?
is it trying to catch or just freespinning real easy?
Its not attempting to fire, its just freespinning, but as far as compression goes, you can hear a very pronounced thump-thump-thump-thump-thump ... and its consistent and even the whole time you crank it.
as far as it flooding, every rx7 i've ever been around has had bad flooding problems... I mean damn they've got like 500cc injectors for such a tiny engine, if it didn't start right away... its almost going to be flooded every time.
as far as holding it wide open while cranking, i've had him crank it and i'm under the hood messing with the throttle trying to listen to a change in cranking. but the ECU not being designed to run the engine being ported like that, that makes perfect sense... but how to get around it to try to get it started ?
05-02-2007, 12:59 PM
#5
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Join Date: Jan 2007
Posts: 39
If you have fuel and spark it should run or least cough. Make sure your timing is at least close. Leading plugs both fire at the same time. Trailing plugs firing at the wrong time should not keep engine from trying to run. You might try running a switch to the fuel pump. When you smell gas, turn the pump off and keep cranking. Sooner or later you should get to the right fuel/air mix and it should try to run, switch the fuel pump back on.
05-02-2007, 01:09 PM
#6
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Join Date: Apr 2005
Posts: 8
Originally Posted by Rotary911Porsche' post='870229' date='May 2 2007, 12:59 PM
If you have fuel and spark it should run or least cough. Make sure your timing is at least close. Leading plugs both fire at the same time. Trailing plugs firing at the wrong time should not keep engine from trying to run. You might try running a switch to the fuel pump. When you smell gas, turn the pump off and keep cranking. Sooner or later you should get to the right fuel/air mix and it should try to run, switch the fuel pump back on.
hey sounds like a good idea... i'll try it and get back to you guys as soon as I get a chance.
i know its got good HOT spark, i nailed myself more than once... lol... but as far as the right air/fuel mixture that switch idea sounds good. i guess i'll triple check the timing again, because that's about the only other thing it could be.
05-05-2007, 05:45 PM
#7
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Join Date: Apr 2005
Posts: 8
well we got it started.... took quite awhile actually.
turns out the thing WILL NOT start using the stock starter ....
we ended up towing it down the road and pop starting it ....
it ended up firing up and idling terribly (heavy porting) ... i'm guessing that we need to set the idle screw so it sits somewhere around 1500-2000 rpm.... if you let your foot off the gas petal it will die, but if you hold it, steady it runs.
questions...
do you need a starter that spins the motor faster than the stock starter ?
we don't know enough about ported rotary engines and such to figure all this stuff out.
and another thing, what is the stock rev limit on an N/A 7 ??? because to my knowledge, every other 7 i've seen, turbo or not on factory electronics fuel cuts at 7500. this one will bury the tach at 8 grand and cuts (i'm guessing 9000-9500?) and this ECU appears to be stock, along with 90% of the electronics in the car.
any opinions or help would be greatly apprecieated, we're hoping to get this thing driveable soon.
thanks
Jacob
turns out the thing WILL NOT start using the stock starter ....
we ended up towing it down the road and pop starting it ....
it ended up firing up and idling terribly (heavy porting) ... i'm guessing that we need to set the idle screw so it sits somewhere around 1500-2000 rpm.... if you let your foot off the gas petal it will die, but if you hold it, steady it runs.
questions...
do you need a starter that spins the motor faster than the stock starter ?
we don't know enough about ported rotary engines and such to figure all this stuff out.
and another thing, what is the stock rev limit on an N/A 7 ??? because to my knowledge, every other 7 i've seen, turbo or not on factory electronics fuel cuts at 7500. this one will bury the tach at 8 grand and cuts (i'm guessing 9000-9500?) and this ECU appears to be stock, along with 90% of the electronics in the car.
any opinions or help would be greatly apprecieated, we're hoping to get this thing driveable soon.
thanks
Jacob
05-05-2007, 10:46 PM
#9
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Join Date: Apr 2005
Posts: 8
Originally Posted by Leetheslacker' post='870558' date='May 5 2007, 06:08 PM
it might have to run a little to run in the seals to make enough compresson to start right.
or the starters bad?
well we had an issue with a fuel leak... turned out to be incorrect clamps, and the 255 walbro, definately wasn't a good combination.... got that all sorted out, tried cranking again, good strong crank and nearly new optima red top, but still no start.
hooked a strap to the 7 and towed it down the road with my firebird at about 20mph, and after a 2nd gear clutch pop it fired right up, managed to set the idle around 1500-1800. Has a very heavy loping idle. Shoots huge fireballs out of the muffler when you revv it up and let off....
We let the car heat up for a few minutes and drove it down the road, took off in 1st gear and shifted to 2nd, and the clutch went out... no idea what went wrong, but you can hear **** rattling around in the bellhousing... probably a broken finger on the pressure plate.
but anyways.... hoping to poke around the internet for a starter that can crank the engine about twice as fast as the factory style starter.... and possibly some hotter spark ... any ideas ?
05-06-2007, 06:18 PM
#10
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Join Date: Jan 2003
Location: Gardena CA
Posts: 199
Originally Posted by tubjub' post='870601' date='May 5 2007, 08:46 PM
well we had an issue with a fuel leak... turned out to be incorrect clamps, and the 255 walbro, definately wasn't a good combination.... got that all sorted out, tried cranking again, good strong crank and nearly new optima red top, but still no start.
hooked a strap to the 7 and towed it down the road with my firebird at about 20mph, and after a 2nd gear clutch pop it fired right up, managed to set the idle around 1500-1800. Has a very heavy loping idle. Shoots huge fireballs out of the muffler when you revv it up and let off....
We let the car heat up for a few minutes and drove it down the road, took off in 1st gear and shifted to 2nd, and the clutch went out... no idea what went wrong, but you can hear **** rattling around in the bellhousing... probably a broken finger on the pressure plate.
but anyways.... hoping to poke around the internet for a starter that can crank the engine about twice as fast as the factory style starter.... and possibly some hotter spark ... any ideas ?
fuel cut will hit at 8100 rpm on a stock ecu.I would also get a msd box for hotter spark easier starting. For a faster starter try running a new momentary switch and relay with a nice fat power wire, bypassing all the old stuff in the IGN switch. It made mine twice as fast. You can also semi hide the switch so you 7 wont get ripped off. dont forget a fuse too!!