Obd cycle

Rachelnajjar · Nov 6, 2018

Heya! Sorry if this isn’t posted in the right spot or if it’s a duplicate thread. I had an account here a few years ago and you folks helped me replace my timing belt so I’m hoping you can help me again. I’m going to look at a 1990 ranger tomorrow, 6 cyl 2.9 L. My boyfriend needs me to look it over for him before he buys it- i know it’s obd1 but I’m not sure what the drive cycle is. If anyone has a link or a step by step that would be great, thanks!

adsm08 · Nov 6, 2018

I'm not sure that the EEC-IV system has a drive cycle the same way OBD2 does.

Why do you need to know that just to look at it?

rusty ol ranger · Nov 6, 2018

Take it for a drive. If it starts/runs/shifts/stops and doeant smoke thats about all you can ask for on an inital lookover

RonD · Nov 6, 2018

1990 2.9l Ranger used a distributor with TFI spark system, the TFI modules would get heat sensitive over time so would need to be replaced

The 2.9l were prone to cracking heads if overheated, or just because, but the 1990 had the later design heads so less prone but not immune
Look for bubbles in radiator on cold engine start up, or overflowing radiator on cold start

1990 EEC-IV may use 2 digit codes or 3 digit codes, OBD1

This pdf covers alot of ground but also has info you will need: https://static.summitracing.com/global/images/instructions/equ-3145.pdf

It is generic but does cover Ford EEC-IV

Rachelnajjar · Nov 6, 2018

adsm08 said:
I'm not sure that the EEC-IV system has a drive cycle the same way OBD2 does.

Why do you need to know that just to look at it?

I like to know what’s wrong with a vehicle before i buy it

Rachelnajjar · Nov 6, 2018

RonD said:
1990 2.9l Ranger used a distributor with TFI spark system, the TFI modules would get heat sensitive over time so would need to be replaced

The 2.9l were prone to cracking heads if overheated, or just because, but the 1990 had the later design heads so less prone but not immune
Look for bubbles in radiator on cold engine start up, or overflowing radiator on cold start

1990 EEC-IV may use 2 digit codes or 3 digit codes, OBD1

This pdf covers alot of ground but also has info you will need: https://static.summitracing.com/global/images/instructions/equ-3145.pdf

It is generic but does cover Ford EEC-IV

Thank you!!! Super helpful. I appreciate it!

adsm08 · Nov 6, 2018

Rachelnajjar said:
I like to know what’s wrong with a vehicle before i buy it

Ok, even running an OBD2 vehicle through a full drive cycle won't always set a code right away.

While it's always nice to know when buying something that old it is best to assume that you won't find all the problems with the initial look over.

Rachelnajjar · Nov 6, 2018

adsm08 said:
Ok, even running an OBD2 vehicle through a full drive cycle won't always set a code right away.

While it's always nice to know when buying something that old it is best to assume that you won't find all the problems with the initial look over.

Nothing wrong with being as informed as possible.

RonD · Nov 6, 2018

Also just a used car buyers tip
All fuel injection computers have a Clear flooded engine routine

Turn key ON, starts up computer
Press gas pedal down to the floor, and hold it down, turns OFF fuel injectors
Turn key to START
Engine should just crank and not start, no fuel, until you release gas pedal from WOT(wide open throttle)

Thats Clear flooded engine routine, allows you to dry out a Flooded Engine

I use it every morning on my high mile 1994(obd1) 4.0l to pump oil thru the engine before it starts, so no dry starts

But it can be used by car buyers with the knowledge of it to get a few dollars off a used car price.

A NO START is not a good sign when buying a used vehicle....................

Knowledge is power, and it is also a test, you are testing Computer, TPS(throttle position sensor), throttle cable, if its stretch test won't work because no WOT, and fuel injectors for leaks or shorts to ground, engine would fire if an injector was leaking
But if seller thinks there was something wrong and wants to knock down the price a bit, no skin off your nose.

OK so can't dress it up as a test, its dishonest, lol.

But at least you know about it now, so when you sell a used car and it doesn't start when buyer tries it, you will know why

adsm08 · Nov 6, 2018

Rachelnajjar said:
Nothing wrong with being as informed as possible.

I'm not saying there is. I am saying that I don't think that A) You understand the true purpose of a drive cycle. and B) that it would be as informative as you seem to think, particularly on the vehicle in question.

Rachelnajjar · Nov 6, 2018

adsm08 said:
I'm not saying there is. I am saying that I don't think that A) You understand the true purpose of a drive cycle. and B) that it would be as informative as you seem to think, particularly on the vehicle in question.

I compile a list of what needs fixed now, what can wait, how much it will cost to fix... not sure what your issue is, friend! I am researching before i buy a car. That’s all.

adsm08 · Nov 6, 2018

I'm not against doing research. I am simply trying to point out that this investigation on this vehicle is likely to yield, at best, incomplete or inaccurate results, due to the nature of the two. EEC-IV isn't like OBDII. It doesn't need a set of parameters met, and then gauge the system and have to see an error so many times etc before the light comes on. It just sees a problem and grounds the bulb. For an EEC-IV system it is just as Rusty said, if it starts, runs, shifts, drives, and doesn't do anything odd during all that you are probably fine.

But even on an OBD2 system the drive cycle isn't going to show you a problem right away. It is only meant to be used to prep the vehicle for an on-board emissions test. Basically it is there to show you that the conditions to test each system have been met at least once since the last time the system was reset.

I firmly believe that knowledge is power, and not enough of it is in the hands of the consumer when it comes to vehicles. I am trying to educate you (and anyone else who reads this) on the purpose of the drive cycle.

dirtymike · Nov 6, 2018

that's some sweet info. Did it to my 87 2.9 after top end rebuild and it reduced the rpm down to 850. I guess the throttle cable has stretched. dirty

Obd cycle

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