1995 4-Runner with cold start & missing/buck problems under load
 

I purchase a 1995 4-Runner with 224 000 KM back in January and with it came two problems,first: difficult to start when engine is cold (also worse when outside temperature is cold like winters) and second: bucking/missing underload specially in cold weather on highways and more notice when engine warming up.

Not knowing history of vehicle maintenance and last owner using aftermarket tune up parts I decided to replace the following:

-Spark plugs=old ones were Champion and tips were melted (wrong temp rating),new ones OEM Denso
-Spark plug wires=old Bosch,new ones OEM Yazaki (same as Denso)
-Rotor=old Standard,new OEM Denso
-Cap=old Standard,new OEM Denso
-Air filter=old made in Israel was dirty,new OEM Denso
-Fuel filter=old made in China,new OEM Denso
-Oxygen sensor=old Bosch was lazy,new OEM Denso

I also ran "Sea Foam engine treatment" in fuel tank,intake and engine oil, 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 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 also did a spark test and 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 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 couldn't get the old Denso PCV valve off to inspect because it's grommet is not flexible anymore, I am afraid to break the grommet and have the small broken bits fall into engine.

I don't have a timing light to inspect for engine bast timing to make sure it's at 5 degrees BTDC with terminals T-E1 shorted together in Diagnosis box and 8 degrees BTDC without. The engine does have a somewhat small rattle at start up (the noise is less noticeable since I switched to OEM Denso oil filter with AWESOME anti-drain back valve) and more notice when engine is cold. The timing chain it's components were never changed and owner always used a Chrysler Mopar white colored oil filter.

The vehicle does have excellent fuel economy of about 500 KM with 65 liter gas tank.I usually re-fuel at 450 KM so there are about 10 liters of fuel left. I use Octane Rating 91 as she runs alot better than regular Octane 87 or 89. Although she doesn't seem to have any power like my old 1985 4-Runner with 22R-E even though this 1995 weighs 1400 Kg and my old 1985 weighed 1600 Kg.

Sorry for the long post but I cannot seem to diagnose the 3 problems which may all be one or three different problems:

1)Hard starting with cold engine
2)Missing or bucking underload more noticeable at higher speeds (highway) and more noticeable when climbing a hill and with colder engine
3)Lack of power (quick acceleration) like my old 4-Runner

Could all 3 problems be lack of proper timing because of timing chain stretch and tensioner wear? is so would re-adjusting engine base timing correct problem until I replace timing chain components? or ECU (EFI computer) automatically re-adjust timing?.

I didn't check fuel pressure regulator and on the second generation 4-Runners (1990-95) you cannot access the re-usable platic washable fuel pump screen/filter from the back passenger seat. Instead the whole gas tank must be dropped.

Here is where I download my free factory service manual:

Free 1995 Toyota 4-Runner Factory Service Manual:

http://rapidshare.com/files/34006966...0.1995.SIL.rar
http://www.the-roo.com/4runner (3VZE engine, 3 liter, V6)

and where I purchased my OEM Toyota parts from this dealership that sells parts for 30% off Toyota USA MSRP:

http://www.1sttoyotaparts.com/partscat.html (10% shipping by Fed Ex or free shipping with $100 & over and 15% shipping to Canada by USPS Mail speak to Don 1-888-271-3948)

When you call and speak to Don tell him Sidney from Nova Scotia sent you. Thanks for the help in advance.

Sidney

cold start
 

Geez Sidney, your out of my league. I can't help you. My 22re 1995 always takes a couple of seconds to start. Do you have emissions test out there? Cat converter, could that be the problem? I also get less than 10L/100 km,s.

cold start
 

Oh yea forgot to mention I bought a timing light at canadian tire, dcheked and adjusted my timing then returned the timing light. I guess I'm real cheap.

No emission test here yet but last year the federal government and Nova Scotia government were seriously thinking about it. The catalytic converter looks rusted out and since the front exhaust pipe now has a hole near the cat, the whole exhaust system will need to be replaced but I have spent too much money on it already.

Canadian Tire's "Loan A Tool Program" doesn't include timing lights so I may do what you did.

I borrowed a "Power Fist" brand of compression tester sold at "Princess Auto" stores in Canada and probably "Harbour Freight" stores in USA and measured the following compression test with engine COLD and throttle wide open:

Cyl
1=165-170 psi
2=200-225
3=200-225
4=200-225

I re-measured #1 and compression was 240, I am aware that the standard psi is 171 and minimum is 142 and the difference between each cylinder shold not be more than 14 psi. The gauge I used (also first gauge I ever used) didn't hold the needle I had to keep an eye on the needle after the third jump of each test as I was told by friend who lent me the tester to take note of third needle jump.

Sidney

I noticed shortly after compression test she started within a split second.

Sidney

Could the timing chain have jumped a tooth causing this problem? I haven't yet removed valve cover or set the crank pulley at 0 DBTC and removed the distributor cover cap to see if the rotor is pointing dead on at spark plug point #1.

Sidney