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Discussion Starter #1
I am perplexed with my 1994 4runner 3.0 liter, 4x4,manual trans. Purchased vehicle at auction. Ran poorly had no oil, no water, blown head gasket, burned valves and worn rings. I rebuilt the entire motor including new cylinder heads (to replace cracked heads). Installed upgraded four spray pattern fuel injectors. Upon starting the engine I had two dead cylinders. The cylinder condition ended up being two malfunctioning injectors. Injectors replaced with Bosch four spray injectors and all cylinders operated properly. Engine idle was not real smooth, but adequate to keep the engine operating.



Cold start up is not on first crank, but generally within a few seconds and goes to 1,200 RPM,s. dropping to 900 RPM within a few minutes. The timing at cold start is 30 or 40 degrees advanced dropping to 4 degrees as the vehicle idles down. Then after several minutes of idle the timing advances to about 14 degrees and stays there. Idle speed ultimately drops to 500 RPM but, can be increased to 750 by turning idle speed adjustment screw at the side of the throttle body housing.


When the throttle is accelerated timing advances further, but the engine stumbles slightly and hesitates. A quick snap of the accelerator results in timing dropping below TDC before advancing out of site. When driving the engine idle is a little rough and the engine lacks power in every gear until the vehicle momentum is scooting along. When adjusting the timing, jumping TE 1 and E 1 had no effect on the timing setting. With the ignition key on, the check engine lamp (CEL) blinked at a constant rapid rate with no indication of any trouble detected. I connected scan tool to diagnostic connector and scan tool said it was not connected and could not read from ECM.



I burned off what I thought to be some bad gas, driving over 100 miles. With the tank down to near a gallon, I filled up with premium fuel. I replaced the battery and alternator, as during testing the equipment showed regulator failure when the air conditioner was turned on. I am down to thinking the ECM is the problem. I hate to buy a used one, not knowing if this is a systemic problem with these older ECMs. Dealer does not have a clue, but would love to have the vehicle to start replacing components and making money. I can find ECMs from $100.00 to over $1,000.00. I am currently stumped! Does anyone have any ideas?
 

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Soylent Green sales
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12,801 Posts
That's a lot of good information, but the only thing I can think of right now is a vacuum leak somewhere.
If you don't get much response maybe post in the 88-95 truck section as well.
 

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Discussion Starter #4
Problem solved

The performance problem ended up being the aftermarket injectors. I bit the bullet and purchased OEM injectors and the vehicle is running fine now.
 

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Soylent Green sales
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12,801 Posts
Its great you figured it out.
Thanks for getting back to us with the solution.
 
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