Engine Problem Challenge
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Engine Problem Challenge
I have an '88 F350 with 351w/C6 (formerly fuel injected) that has been converted to carb. (The computer and most sensors did not pass testing) The ignition which was tied into the old computer system was swapped over to a DUI distributor. The engine runs pretty smooth but seems to produce little power.
When I took it to the shop for inspection and replacement muffler I asked them to check out the transmission and engine for loss of power. They called me back later because they wanted to SHOW me what they found.
If they ground out the #1 cylinder spark, the engine runs better. The shop owner even called in a retired Ford tech as a favor to check it out. They all told me they had never seen anything like it.
1) Compression is even on all cylinders
2) Timing chain was replaced and verified before reassembly
3) Plugs, wires, cap, rotor, module, coil, are all new
4) Leak down test indicated nothing.
Anyone have any ideas what to check? This truck has significantly less power that my '79 F150 with a 351M. I would love to have some of you experts to help me with this one!
When I took it to the shop for inspection and replacement muffler I asked them to check out the transmission and engine for loss of power. They called me back later because they wanted to SHOW me what they found.
If they ground out the #1 cylinder spark, the engine runs better. The shop owner even called in a retired Ford tech as a favor to check it out. They all told me they had never seen anything like it.
1) Compression is even on all cylinders
2) Timing chain was replaced and verified before reassembly
3) Plugs, wires, cap, rotor, module, coil, are all new
4) Leak down test indicated nothing.
Anyone have any ideas what to check? This truck has significantly less power that my '79 F150 with a 351M. I would love to have some of you experts to help me with this one!
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Sorry about the delay as I only get one day a week to work on anything. The fuel mileage seems to be similar to my old F150, but it has only been on one trip to the hardware store. There is a significant amount of power loss on a hill. Flooring the gas does nothing to give more power, but you can hear and feel the engine working harder.
The firing order has been set at 1-3-7-2-6-5-4-8.
Anyone with some testing ideas?
The firing order has been set at 1-3-7-2-6-5-4-8.
Anyone with some testing ideas?
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Check to make sure you don't have spark plug wires running parallel to one another. This will induce spark into the wrong plug sometimes.
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Thanks to everyone for the responses! The engine runs pretty smooth, but grounding the #1 will smooth out the engine like it is off. I will check the wires again to see if they are cross-firing as that is something I haven't verified at least a few times.
In regards to the firing order, there is another that this motor can run on? That would be interesting.
In regards to the firing order, there is another that this motor can run on? That would be interesting.
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I forgot to add this one...the mechanical and vacuum advance appear to work and playing around with the v-advance didn't help me produce any significant power increase. The shop I took the truck to said the harmonic balancer marks did not slip.
If I pay another shop to look at it, since I do not have the time to dedicate to this, what should I look or ask for? My thought is to take it to an old-school shop as many newer techs are experienced in only the computer systems which mine no longer has.
If I pay another shop to look at it, since I do not have the time to dedicate to this, what should I look or ask for? My thought is to take it to an old-school shop as many newer techs are experienced in only the computer systems which mine no longer has.
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Ok how about this (I'm grabbing at straws here), the firing order is designed so that the engine has balanced "power" strokes, if the cylinder that is opposite of #1 is not firing, then you are only running on 7 cylinders, thus no power, when you have it idleing and you eliminate spark to #1 it smooths out the idle because now you are running on 6 "balanced power stroke" cylinders. Look at the cylinder that is opposite (in the firing order) from #1.
Start the engine and begin pulling wires from one plug at a time (don't get zapped), if idle changes when you pull a plug wire then that cylinder is not the problem, put the wire back on and move to the next.
Start the engine and begin pulling wires from one plug at a time (don't get zapped), if idle changes when you pull a plug wire then that cylinder is not the problem, put the wire back on and move to the next.
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Oh ya and to answer your question about the different firing orders. Yes there are two possible for a small block ford, it depends (someone correct me if I'm wrong) on the camshaft settings (weather it has a 302 cam or a 351 cam?).
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Depends on if it's a 302 or 351w or from a car or truck.
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Thanks to Conanski as I tried changing the firing order. However,it was backfiring while cranking which spooked me. The last time I had the timing off the muffler actually turned itself inside out.
BOOM!
Thanks Cowmilker. That is something I haven't thought of and will follow your idea tomorrow.
BOOM!Thanks Cowmilker. That is something I haven't thought of and will follow your idea tomorrow.