Does a 302 need some back pressure?
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Does a 302 need some back pressure?
I have a 89 F150 4x4 with a 302 bored .20 over. I put shorty headers on it and then a "custom" free flow exhaust that is just strait pipes that come out behind the rear tire. While I love the way it sounds, I am wondering if I need to put some kindof muffler on it to give it some back pressure?
I am having trouble with it loading up and even flooding if you try to start it after it has warmed up.
I was wondering about the egr. I don't know if it is still working or not. I don't remember hooking any think but the O2 senor up when I did the exhaust work.
I now I had a vac. leak on the hose that goes to the temp control for the A/C and heater. But I have fixed that so I don't think that is the problem any more.
I am having trouble with it loading up and even flooding if you try to start it after it has warmed up.
I was wondering about the egr. I don't know if it is still working or not. I don't remember hooking any think but the O2 senor up when I did the exhaust work.
I now I had a vac. leak on the hose that goes to the temp control for the A/C and heater. But I have fixed that so I don't think that is the problem any more.
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From: Edmonton, AB Canada
I had that problem on my 92, with a full exhuast system. Turned out to be the coolant temp sensor. The motor thinks that the truck is cold so it puts more fuel in when starting after warm. The one that controlls the computer is located in a tee coming out of the front of the intake.
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From: Central PA
I had dual cats and 2 1/4 pipes on a 89 302. when I increased the pipe size to 2 1/ 2 the truck didn't seem to run as good , and MPG went down . After 15 trucks of various configurations and 600000 miles I've found that the shorty headers and a bassani Y-pipe is way to then split to duals .It just seems to preform the best as well as MPG .
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From: Central NY
No/low backpressure will shift the hp/torque curves into the upper rpm range, You will notice much lower power taking off from a stop since you will have significantly less torque available at the lower rpms.
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Okay. But I have most of the stock exhaust on there with the exception: Just after the muffler I just put a turn down instead of the curvy screwy piece. But the other day the Emissions return tube (from the Y-pipe to the EGR valve... area) snapped and I got a lot of low end power. My 0-60 time went down to 16 seconds. Now that its fixed its up to 23 seconds. How do I get that 7 seconds back without smelling exhaust every time I stop?
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I would look into replacing your cat, it sounds like its pluged. If you gain performance with an open section infront of your cat, then its not flowing well threw it, or you muffler is plugged up. If you dont have to worry about emisions, cut it off like I did and install an aftermarket exhaust. That will get you 7 seconds back. I have a new stock 302, shorty headers with a 2-1/2" y-pipe that I built that runs into a flowmaster kit for these trucks, and a k&n FIPK kit. Kept up to a new dodge with a hemi in it with 3.50 gears in the 9" and 33's.
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"Turned out to be the coolant temp sensor."
So you think this could be the problem? What about the EGR what does it hook into?
I am going to try to pull some codes on it this after noon. I haven't done any thing to the intake except put the mass air conversion on it, with the new ecm. That didn't really help me much, but my wallet is $700 lighter.
I have a 6inch suspenion 3inch body lift and running 38.5x16x15 Mickeythompson claws and I have 5.13 gears in the pumkin's.
So you think this could be the problem? What about the EGR what does it hook into?
I am going to try to pull some codes on it this after noon. I haven't done any thing to the intake except put the mass air conversion on it, with the new ecm. That didn't really help me much, but my wallet is $700 lighter.
I have a 6inch suspenion 3inch body lift and running 38.5x16x15 Mickeythompson claws and I have 5.13 gears in the pumkin's.
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From: Edmonton, AB Canada
The egr is plumbed into your intake to recirculate exhaust gases. This would not cause flooding on a warm start up, it would make your idle rough, but smooth out as you increase engine speed. Since there is no fuel run threw the egr and emmisions stuff, it would not cause your engine to flood, or really make starting all that difficult. If the egr is stuck wide open, you would notice some extremely rough idle, no power, and possibly even stall. I would put my money on the coolant temp sensor, and to check it when its warm, i believe its the green/white wire off of the sensor, put a voltmeter on it and ground and see what the voltage output is when the truck is cold and warm. At operating temp of 180 degrees, the voltage should be 0.8 volts, and at 32 degrees it should be around 4.o volts. A hand reference chart for this is http://fordfuelinjection.com/index.php?p=28. The symptoms are wrong to me to be egr.
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From: Edmonton, AB Canada
The egr valve itself is located up near the throttle body on the upper intake, passenger side. From what I can tell from looking at how the pipes are run, the exhaust gases go from the head up threw the intake up to the egr and then back into the upper intake via the valve. If the smog pump is not there, then air is not getting forced into the egr crossover pipe at the back of the heads, or down to the cat depending on where the computer wants the flow to go. I dont think this would affect flooding while warm though. It might cause some mileage decreases, but judging from the rest of the mods on your truck I dont think that is a big concern for you. As for it affecting your truck in total, I have no idea, but I dont think this is the source of your flooding while warm problem.
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From: Edmonton, AB Canada
I am also running headers, but I still have the smog pump hooked up. The only thing that I dont have is the small diameter pipe down to the cat, cause I dont have a cat anymore. My truck seems to run just fine. I have to throw the scanner on there still to work out some other bugs to make the check engine light to stop flashing at me once and a while, but thats more in my wiring than anything else when I transplanted the 302 for the I6. Like I said, my truck doesnt have any issues of flooding while warm after I changed the faulty coolant temp sensor.
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Well I scanned my truck this afternoon with a computer and it gave me codes 51 and 85. That was with the KOEO test.
Then I did the KOER and received code 98, but I didn't let the truck warm all the way up because of time constrants and the fact that the temp gauge doesn't work so I don't know if its at normal operating temp or not.
The scanner said code 51 was coolant temp signal high ckt open
and for 85 it said 0=CANP CKT Fault/C=fuel at lean I think it said fuel I can't read my writting now.
Then on 98 it said DTC Present (FMEM)/EP CKT Fault
I also looked for the temp coolant sensor but couldn't find it. It may be on the driver's side of the intake.
I found it on my 95 bronco, but the hose that hooks into it on my bronco goes back up by the distributor on my 89 truck.
Then I did the KOER and received code 98, but I didn't let the truck warm all the way up because of time constrants and the fact that the temp gauge doesn't work so I don't know if its at normal operating temp or not.
The scanner said code 51 was coolant temp signal high ckt open
and for 85 it said 0=CANP CKT Fault/C=fuel at lean I think it said fuel I can't read my writting now.
Then on 98 it said DTC Present (FMEM)/EP CKT Fault
I also looked for the temp coolant sensor but couldn't find it. It may be on the driver's side of the intake.
I found it on my 95 bronco, but the hose that hooks into it on my bronco goes back up by the distributor on my 89 truck.
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From: Davis & Newcastle, CA
I can't offer much help as far as a solution here, but I will clarify those codes:
51 - ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
85 - Canister Purge Solenoid circuit failure.
98 (KOER) - Hard fault present.
The last one doesn't make sense to me, but the first 1 does seem to coincide with what Tdvjensen was saying about your coolant temp sensor.
-Chris
51 - ECT sensor signal is greater than the Self-Test maximum of 4.6 volts.
85 - Canister Purge Solenoid circuit failure.
98 (KOER) - Hard fault present.
The last one doesn't make sense to me, but the first 1 does seem to coincide with what Tdvjensen was saying about your coolant temp sensor.
-Chris