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1995 4-Runner bucking/missing under load

I purchased a 1995 4-Runner with 224 000 KM back in January 2008 and with it came 3 problems which I didn=92t know about:

1)Difficult to start when engine is cold (also worse when outside temperature is cold like winters), cranks fine 2)Bucking/missing under load specially in cold weather on highways and more noticeable when engine warming up but still present with warm engine 3)Idles fine at 750 rpm but once warmed up if you shut engine off and re-start idles low (not O2 sensor because I changed it), also idles low if coming from highway speeds and rpms are kept low while slowing down and not using brakes as fast and hard, meaning gradually coming to a stop. If using brakes quickly and hard usually she idles fine at 750 rpm I replaced the following parts (90% OEM Toyota) because most needed replacing and hoping that it would solve my above 3 problems as well but they didn=92t: Complete tune up parts (spark plugs, wires, rotor, dist cap, PCV valve & grommet, air filter, fuel filter, O2 sensor, cleaned AFM housing and throttle body) & ran Sea Foam several times in the fuel, oil and vacuum system. The plastic washable/re-usable fuel pump filter (inside the gas tank) is in excellent condition. Main fuel line, fuel pump bracket, fuel filler pipe (my mechanic replaced these parts) Complete exhaust system, front to back, again all OEM except for stainless Magnaflow cat Head gasket (head was corroded from prior head gasket failure where prior owner=92s mechanic didn=92t have head examined), head was welded and shaved, timing chain kit was replaced (an engine rebuilder shop replaced these parts) I found 2 ground corroded/rusted wires, one connected on firewall and engine hoist hook (4th spark plug wire) and the other was broken because the battery was loose so the wire broke between the negative battery terminal and passenger fender wall. I replaced both wires. I pulled the ECU (EFI computer codes) and nothing came up, I also measured the voltages and resistance at each ECU wire and compared with FSM (factory service manual) still nothing, I also did a spark test and compression test. I used a timing light to check for engine base timing and it=92s at 5 degrees BTDC with T-E1 shorted in diagnosis box. My mechanic took these fuel pressure readings after replacing main fuel line but before the fuel pump bracket and am not sure where he placed his fuel pressure tester: Dead head=3D55 PSI (the factory service manual=3D38-44 PSI) Idle=3D36 PSI ( the factory service manual=3D38-44 PSI) Idle without vacuum=3D40 PSI (the factory service manual=3D33 PSI avg or 23-37 PSI) I measured the resistance on the cold start injector, cold start injector time switch, intake air temp sensor, water temp sensor for ECU, AFM and TPS. I measured the wire harness for each of the above parts and nothing. I unbolted the cold start injector and moved it back about 1" and had a friend crank cold engine and fuel spray came out and was uniform. I also removed cold start injector from vehicle and dipped in Sea Foam for 10 minutes even though nozzle tip and it's fuel line entrance was clean. When I say it's difficult to start with cold engine I mean the engine turns over but doesn't start until about 3 seconds (more in colder weather) and once engine is warm (after driving) she will start sooner but not instantly like Toyotas are known for. I found that when engine is REALLY COLD (in cold winters) I crank it for 2 seconds then stop then crank then she will start if I attempt another technique she will start then shut off right away. I know for an engine to run you need the 3 basics: fuel, spark and air. When I jumper Fp (fuel pump) terminal and B+ (battery) terminals in the diagnosis box thereby bypassing the AFM power switch and circuit opening relay (fuel pump relay) found behind the glove compartment, the engine starts faster almost instantly. The AFM and circuit opening relay are fine as I measured their resistance and voltages and compared the readings with the service manual as I stated earlier. I was told it may be a vacuum leak or EGR valve but I don=92t have an unlit propane torch to use and visually inspecting the vacuum lines I didn=92t see any obvious cracks. I do have the factory service manual but am at a lost hence why my post, if it may be an air problem how do I find it? Can anyone help me?, I have tons of very resourceful info dedicated to Toyota 4-Runners/pickups like free: service manual downloads, EPC catalog downloads, discussion sites, cross referencing parts, places to buy OEM parts for very low price, etc. Sidney=AE =99 Repairs TV's,VCR's,home/car audio out of my apartment E-mail:sidneybek(at)yahoo.com Dartmouth,Nova Scotia Canada 1995 Toyota 4-Runner, 22R-E, G52 with 235 000 KM
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sidneybek
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Sorry for the original messed up post.

I purchased a 1995 4-Runner with 224 000 KM back in January 2008 and with it came 3 problems which I didn=92t know about:

1)Difficult to start when engine is cold (also worse when outside temperature is cold like winters), cranks fine 2)Bucking/missing under load specially in cold weather on highways and more noticeable when engine warming up but still present with warm engine 3)Idles fine at 750 rpm but once warmed up if you shut engine off and re-start idles low (not O2 sensor because I changed it), also idles low if coming from highway speeds and rpms are kept low while slowing down and not using brakes as fast and hard, meaning gradually coming to a stop. If using brakes quickly and hard usually she idles fine at 750 rpm

I replaced the following parts (90% OEM Toyota) because most needed replacing and hoping that it would solve my above 3 problems as well but they didn=92t:

Complete tune up parts (spark plugs, wires, rotor, dist cap, PCV valve & grommet, air filter, fuel filter, O2 sensor, cleaned AFM housing and throttle body) & ran Sea Foam several times in the fuel, oil and vacuum system. The plastic washable/re-usable fuel pump filter (inside the gas tank) is in excellent condition.

Main fuel line, fuel pump bracket, fuel filler pipe (my mechanic replaced these parts)

Complete exhaust system, front to back, again all OEM except for stainless Magnaflow cat

Head gasket (head was corroded from prior head gasket failure where prior owner=92s mechanic didn=92t have head examined), head was welded and shaved, timing chain kit was replaced (an engine rebuilder shop replaced these parts)

I found 2 ground corroded/rusted wires, one connected on firewall and engine hoist hook (4th spark plug wire) and the other was broken because the battery was loose so the wire broke between the negative battery terminal and passenger fender wall. I replaced both wires.

I pulled the ECU (EFI computer codes) and nothing came up, I also measured the voltages and resistance at each ECU wire and compared with FSM (factory service manual) still nothing, I also did a spark test and compression test. I used a timing light to check for engine base timing and it=92s at 5 degrees BTDC with T-E1 shorted in diagnosis box. My mechanic took these fuel pressure readings after replacing main fuel line but before the fuel pump bracket and am not sure where he placed his fuel pressure tester:

Dead head=3D55 PSI (the factory service manual=3D38-44 PSI) Idle=3D36 PSI ( the factory service manual=3D38-44 PSI) Idle without vacuum=3D40 PSI (the factory service manual=3D33 PSI avg or

23-37 PSI)

I measured the resistance on the cold start injector, cold start injector time switch, intake air temp sensor, water temp sensor for ECU, AFM and TPS. I measured the wire harness for each of the above parts and nothing. I unbolted the cold start injector and moved it back about 1" and had a friend crank cold engine and fuel spray came out and was uniform. I also removed cold start injector from vehicle and dipped in Sea Foam for 10 minutes even though nozzle tip and it's fuel line entrance was clean.

When I say it's difficult to start with cold engine I mean the engine turns over but doesn't start until about 3 seconds (more in colder weather) and once engine is warm (after driving) she will start sooner but not instantly like Toyotas are known for. I found that when engine is REALLY COLD (in cold winters) I crank it for 2 seconds then stop then crank then she will start if I attempt another technique she will start then shut off right away.

I know for an engine to run you need the 3 basics: fuel, spark and air. When I jumper Fp (fuel pump) terminal and B+ (battery) terminals in the diagnosis box thereby bypassing the AFM power switch and circuit opening relay (fuel pump relay) found behind the glove compartment, the engine starts faster almost instantly. The AFM and circuit opening relay are fine as I measured their resistance and voltages and compared the readings with the service manual as I stated earlier.

I was told it may be a vacuum leak or EGR valve but I don=92t have an unlit propane torch to use and visually inspecting the vacuum lines I didn=92t see any obvious cracks. I do have the factory service manual but am at a lost hence why my post, if it may be an air problem how do I find it? Can anyone help me?, I have tons of very resourceful info dedicated to Toyota 4-Runners/pickups like free: service manual downloads, EPC catalog downloads, discussion sites, cross referencing parts, places to buy OEM parts for very low price, etc.

Sidney=AE =99 Repairs TV's,VCR's,home/car audio out of my apartment E-mail:sidneybek(at)yahoo.com Dartmouth,Nova Scotia Canada

1995 Toyota 4-Runner, 22R-E, G52 with 235 000 KM
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sidneybek

Reply to
Jim Behning

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