Quad 4 DOHC wont start
Kage25
03-13-2005, 08:56 PM
I have a 1993 Acheiva with a 2.3 Quad 4 DOHC. Ive been working on it no stop trying to figure out what is wrong. Checked the timing and it all looked good. I pulled the fule rail and injectors to check them, they all seem to be working and spraying. Put them back in and the car still wont start(acts like it wants to). So we pulled the Fule rail and with injectors again. When we turned the engin over it fired right up. Just wont run with the injectors and the fule rail in place. As long as we hold the injectors and rail out and above the cylinders it will run but rough....Any Ideas(Fule pressure regulator, weak fuel pump?)
95OldsHO
03-14-2005, 08:03 AM
The coils under the top plate/engine cover are known for going bad, its possible they or the module are failing or giving out a weak spark due to a weak connection somewhere..most quad 4 guys would probaly direct you here first if the coils are the original ones.. the coils were changed at some point, I cant remember what year things changed or which color coil housing is the better of the two, but I think it was the one that is greyish in color, maybe someone can chime in here and verify that.
Bad throttle position sensor could cause this problem I believe also..
With all parts in place and cranking it over you say it "acts like it wants to start" is there a raw fuel smell present at the same time after cranking it over for a bit? Im assuming youve tried starting with the gas pedal depressed, if so there should be a "flooded car/raw fuel" smell after trying to start the car, usually you can get a good wiff of it in back of the car from the exhaust if the fuel system is working.
Clogged intake? It almost sounds to me like it is starving for air, because you say while holding the injectors away from the cyl. head it will run, almost like a backwards vac. leak- instead of giving too much air it is allowing the engine to breathe. Might check out the throttle body/intake and clean it up if needed, maybe its not flowing air like it should -assuming you havent tried to start with the pedal down. If you havent yet try starting it without the intake on, put your hand over/near the throttle body and be sure its sucking in air good and strong.
Check the plugs? make sure they all look normal, and the gaps are correct- also loosing an electrode or two can cause this kind of no start problem. Look over the injector wires/connector make sure they are grounding out somewhere when installed on the engine.
Could be a bad regulator, possibly drowning out the spark with fuel, crank it over a bit, and pull a plug or two and see if they look wet/have a raw fuel smell to them... if too much fuel is being supplied there should be either a raw fuel smell while cranking it over, or on the spark plugs.
Bad throttle position sensor could cause this problem I believe also..
With all parts in place and cranking it over you say it "acts like it wants to start" is there a raw fuel smell present at the same time after cranking it over for a bit? Im assuming youve tried starting with the gas pedal depressed, if so there should be a "flooded car/raw fuel" smell after trying to start the car, usually you can get a good wiff of it in back of the car from the exhaust if the fuel system is working.
Clogged intake? It almost sounds to me like it is starving for air, because you say while holding the injectors away from the cyl. head it will run, almost like a backwards vac. leak- instead of giving too much air it is allowing the engine to breathe. Might check out the throttle body/intake and clean it up if needed, maybe its not flowing air like it should -assuming you havent tried to start with the pedal down. If you havent yet try starting it without the intake on, put your hand over/near the throttle body and be sure its sucking in air good and strong.
Check the plugs? make sure they all look normal, and the gaps are correct- also loosing an electrode or two can cause this kind of no start problem. Look over the injector wires/connector make sure they are grounding out somewhere when installed on the engine.
Could be a bad regulator, possibly drowning out the spark with fuel, crank it over a bit, and pull a plug or two and see if they look wet/have a raw fuel smell to them... if too much fuel is being supplied there should be either a raw fuel smell while cranking it over, or on the spark plugs.
Kage25
03-14-2005, 11:32 PM
also can anyone tell me how to line up the two cams and cranks together so i can know how to check if they sliped or jumped a notck it is a chain and gear setup
95OldsHO
03-17-2005, 11:36 AM
Your going to want a manual if your getting that deep into the motor, its a good idea anyhow... Haynes are good, but the Chilton are a bit better, both would have this info.
Its been awhile but if memory serves me correctly the gear on the crank has a little "dimple" in it, and the block has a mark to match things up. The cams have a small hole in them and there are tools sold(on ebay sometimes)to hold these in place while working on the motor, the "tools" are basically a pin that goes into the cam gear and then extends into the head(guessing on that, not %100 sure what they extend into, must be the head/chain cover I figure). If you line up the mark on the crank gear and block, and have the cam gears at the correct spot so that you can insert a pin/screwdriver/whatever through the cam gear and into the head then the motor should be timed correctly. This is just from memory and like I said its been awhile, probably best to double check it with a manual, Im too lazy to go get mine =)
Can find a ton of very good useful info on the quad 2.3 and 2.4 motors at: www.quad4forums.com the faq section is the best place to start.
Its been awhile but if memory serves me correctly the gear on the crank has a little "dimple" in it, and the block has a mark to match things up. The cams have a small hole in them and there are tools sold(on ebay sometimes)to hold these in place while working on the motor, the "tools" are basically a pin that goes into the cam gear and then extends into the head(guessing on that, not %100 sure what they extend into, must be the head/chain cover I figure). If you line up the mark on the crank gear and block, and have the cam gears at the correct spot so that you can insert a pin/screwdriver/whatever through the cam gear and into the head then the motor should be timed correctly. This is just from memory and like I said its been awhile, probably best to double check it with a manual, Im too lazy to go get mine =)
Can find a ton of very good useful info on the quad 2.3 and 2.4 motors at: www.quad4forums.com the faq section is the best place to start.
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