Hello,

I am having issues with my 1990 ford ranger, 2.9L V6 Manual Tranny, 126000 miles. Hope someone can help me.

Heres the deal....

First, my truck runs great when its cold and been sitting overnight, around 30 minutes of driving, it starts acting up. Second, failed HC emissions test at idle, passing is 220ppm, reading 1475ppm. On the top end, it tested out fine, no problems This was tested before idling problem progressed into below problems.

The engine accelerates fine, no loss of power, but when I let off the gas in gear, the tach starts jumping and the engine sputters and pops, I can hit the gas again and it returns to normal. As long as I am accelerating, no problems. Check engine light would come on and off, but never just stay on. I come to a stop light, and put in N, sometimes it returns to idle with no problems, but more time than not, it dies. I have to restart the engine, then it will die again, after three or four times of this, I can get it going again, then it repeats the process. Bottom line, it wont stay idling, when it does, its maybe for 20 seconds or less. Sometimes it will idle for 10 minutes. In addition, I have had no reduction in fuel mileage. Runs great on the freeway, no problems at all. I have found that is runs the best, in the morning, for 20-30 minutes then the idling problems arise. That isnt always the case, but more times than not it just wont idle, it just wants to die when engine is brought down to idle or decelleration or shifting down in gears. In addition, it really does matter whether the engine is hot or cold either.


Here is what I have done.

Put on code reader - code read TPS sensor, bad. Replaced, fixed check engine light problem.

Replaced cap and rotor and spark plugs. Checked all plugs after 2000 miles, all burning clean.Checked all vacuum lines, cleaned out throttle body, air cleaner is good, fuel filter is recent.

Still same problems.

I hope i have provided enough information for someone to begin to help. If there are any questions, please ask.

Thanks for all your help

 

Checked all vacuum lines? Does this mean you checked it with a gauge off a main tee on left rear corner of upper intake manifold among other checks? Make sure to check the brake booster grommet. & have you modded the engine at all? Such as yank hoses from sensors? Other than that, something probably needs cleaning or I'm forgetting some stuff. O yeah, spark plug wires, for starters and check sensor plugs & such for corrosion. Beyond that, the O2 & cat come to mind, but the cat would usually glow red hot when it plugs that bad.

 

Uhh, I don't want to be negative, or alarming, but it's just good practice to watch the fluids for contaminants on any engine whenever you do the routine checks. Anyway, I don't think this is likely from your post, but the symptoms do closely match an 86 I was given some years ago. Cause was likely a bad fuel regulator screwing up the oil & kept going like that for a few thousand miles. The heads cracked and we scrapped it as the tranny rebuild sucked big-time too. Another symptom on that one was the cab reeked to such an extant that the heater core was probably going bad too. Easy fix of a few minutes & about $25 with new hoses or bypass it with a flush kit. Anyway, better safe than sorry. Yours sounds nicer than my old 86.

 

failed HC emissions test at idle, passing is 220ppm, reading 1475ppm

Your running rich, 1475 is basically raw fuel coming out of the exhaust. clean the backside of the throttle valve. clean your idle air control. I've seen these symptoms and its almost always the backside of the throttle valve is gunked up.

 

A sticking throttle plate should effect the amount of fuel the engine uses in relation to the air entering the engine. However, cleaning it is always a good idea, and it may help. Bad O2 sensors would be at the top of my list. Those should be replaced every 60,000 miles on your rig.

 

Check the thermostat ( temp gauge reading cold ) and the temperature sender for the computer .

 

you might be in open loop rich

 

Welcome to FTE.

Good trouble shooting so far & good idea to scan for trouble codes. Have you posted ALL the code numbers you found & the sequence in which they were retrieved????

You may have more than one problem & I like all the suggetions so far.

With the high HC reading at idle & it running ok at speed, maybe the fuel pressure regulator belongs on your suspect list too. Pull it's vacuum line connection & inspect it for the presents of raw fuel. If it's wet with fuel, the pressure regulators diaphragm is leaking, so replace the FP regulator.

If you don't find a leak, check the fuel pressure with a gauge.

Just another thought for your suspect list. Let us know what you find.