Ok, so I started my truck up yesterday and it idled but it would fluctuate from a regular idle to a very low idle numerous times before it finally died. It does this everytime I start it up. I changed the fuel filter today and it still does the same thing. Any help?

 

1998 Ranger 2.5L 4 cyl. Standard

 

i have the same problem but mines a 1993 v6 4.0

 

Most common problem is the IAC valve.

 

ill look into that thanks... just to clarify.. my idling issue is while in drive (auto) and only happens sometimes... i've changed both O2 sensors, MAF... check engine light still on as well..

 

check the idle air controller

you could also have a charging issue

 

what do you mean charging issue ? can you explain a little more thanks...just enough so i can maybe google it..

 

your alternator might be failing

it is probably producing just enough voltage at idle when in neutral

but put it in drive , you are putting a load on the engine ,, that the spark plugs are barely firing

 

When it running weird, take a hammer and tap on the iac. If it is the iac i should smooth out.

 

I ended up replacing the DPFE Sensor, the fuel filter, the manifold air intake sensor, and another sensor right beside the DPFE sensor that looks like a small cylinder or canister. It fixed the problem. Hope that helps.

However, the DPFE Sensor and the fuel fitler were not the problem but it never hurts to check them out. A mechanic actually had to plug up his machine and find out that the other two were the problem.

 

cheese man, wouldn't the codes show if the altnerator was failing ?

 

thanks rfen... i'll look into that...

 

not nesessarliy ,, the computer only monitors the charge output

if the alternator was putting out a lower charge rate that what was programmed to monitor

then the computer will illuminate the battery light in the dash

any automotive shop can hook up a charge monitor to it while the engine is running

then they do a load test
lights/ high beams / turn signals / hazards / fog lights / heater/ air conditioning / tranny in drive ETC