Check engine light 1st gen

[SizeMatters]

Hey everybody new here on the forum. I got a 91 mazda Navajo stock under the hood. My check engine light comes on sometimes but will go right off if I mash down on the gas for a second. Any ideas why ??? Thanks

 

[MrShorty]

Best first step will be to pull codes from the computer. We have a handful of instruction threads in the stickies in this forum, the Under the Hood forum, and/or the EEC-IV forum which show how to do this with nothing more specialized than a paper clip.

 

[SizeMatters]

Well first thanks for the reply. Okay I thought there was OBD 1 and OBD 2 . So are you saying that my truck is EEC-IV ?? If so thanks I'll look up how to read codes for free. Just thought someone might have run across the problem before and have a quick answer....

 

[Anime]

Sometimes the on/off CEL is the throttle position sensor going bad, other times it might just be a dirty mass airflow sensor, or even something as bad as the PCM iteself going bad from leaking capacitors.

Easiest fix is definitely to get the codes read, if it's a CEL, it's because something is out of spec and the PCM will tell you what it is via the code. If you get multiple codes, you'll have to make a guess as to what the real cause is, or just look them up and see what they usuall indicate, or ask here and you'll get advice.

 

[SizeMatters]

Where the heck is the plug so can check these codes !!! Don't know where to look !!!

 

[MrShorty]

Under the hood, passenger side. Often through years of no use, it will get tucked down into the wiring between the power distribution box and the heater fan.

 

[SizeMatters]

Cool Thank You MrShorty.... Found it checked and got 54

Intake Air Temperature (IAT) or Vane Air Temperature (VAT) signal high - IAT VAT
Know what that means ??? Like I said the light only comes on for a few seconds then goes off. Replace it or wait to see if the light comes on and stays on.....

 

[MrShorty]

Indicates that the intake air temperature thermistor is reading too hot. Was it a KOEO or CM code (see my notes on pulling EEC-IV codes if you are unsure how to distinguish)? Possible causes would start with a faulty sensor or a short between the IAT and the PCM.

 

[SizeMatters]

it was KOEO code. I'll pick up a new sensor put it in and see if that does it. wiring all looks to be in real nice shape.Just got this rig a few weeks ago really nice for it's age ! 12 inch lift 35" tires still trying to figure out the gear ratios in the differentials short of opening them up. I think they are stock , it's kind slow unless you get into the gas real good....