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Old 11-15-2009, 06:36 PM
playaforiife playaforiife is offline
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Posts: 7
Default 2.9 wont rev at all. starts and idles (low) but NO rev above

1990 ford ranger 2.9

Just bought as a fixer, now i have to fix. but stumped

Truck Starts and idles, But very low like 500 rpm. When i hit the gas it will sometimes (30 percent of the time) Rev to maybe 700-800 rms at wot.

Its not a pettal issue, as i go out and manually open thorttle and still nothing.

It was running good yesterday. idle was low so i tightend the screw and raised it. Practially maxed the screw out for a 900 idle.

The sellers said they think its the TPS Not sure if this is correct or if i can check it. Ill do a search for that.

The vehicle has no maf, not sure if it should, or if not this engine. I feel like it should tho. And on the intake box area there are wires that are not connected to anything.

Any ideas guys? Thanks

I will check back every hour till fixed =)

Had an 86 stx about ten years ago. Best truck i ever owned. Im glad to be back in the ranger game, and excited to get past these hick-ups
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Old 11-16-2009, 12:28 PM
playaforiife playaforiife is offline
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Posts: 7

pulled codes...

23 - tps
67 - neutral safty switch

old codes stored were

22 - map
51 - ect sensor
53 - tps
54 - act
67 - neutral safty
96 - fuel pump secandary

Seems like a ton of codes. Is there something that could be at fault and causeing these others to go off?
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Old 11-16-2009, 09:25 PM
playaforiife playaforiife is offline
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Dang no help?
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Old 11-17-2009, 01:21 PM
jadavis1992 jadavis1992 is offline
Ford Motor Company
Join Date: Nov 2009
Posts: 130

the tps code will show up if your idle is not set right so thats iffy, it could be that or not. on my '86 with a 2.9 kinda the same thing it had low fuel pressure and advanced auto parts said that it may need a secondary in-line fuel pump and i got it and it runs fine now. im not saying that that is the problem check your fuel pressure first. and before this incident i never heard of two fuel pumps.
'86 Ford Ranger Super Cab 4x4
2.9 V-6
6in Suspension lift
500 watt JL audio amp
Rockford Fosgate 10" sub
Kenwood kdcx492 head unit
New Holland Red
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Old 11-18-2009, 12:24 AM
Yrac Yrac is offline
Join Date: May 2009
Posts: 341

I'd do some pricing on the senors, a new tps or map has got to be easier to install then an inline fuel pump.
'88 STX Super Cab 4x4
2.9 5spd 180,000 miles
Crappy Paint, Worn Parts,
Fix'em as they Break
when Nowhere is Now Here
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Old 11-18-2009, 11:02 AM
Psychopete Psychopete is offline
Psycho Pete
Join Date: Jun 2009
Posts: 1,488

Could also be a bad reference voltage or ground. With that many stored memory codes, I would at least test some things before hit and miss diagnosing. Often times with wiring that old, sometimes the problem is the not sensor itself. I've replaced a ton of sensors in the past and it sucks to spend the money to replace a good part.

TPS can be tested with an analog volt meter, it is a "variable resistor". Check the reference voltage (+5 volts), signal to ecm should be around (+.9v ~ 5v) and should sweep smoothly through that range from idle to WOT, and check the ground. Test is typically done with the key on engine off.

Screw on the throttle is not an idle adjustment, but the setting for the base TPS voltage. It is best to leave this screw alone as the computer is what controls the idle. If it is off, it will have you working in circles.

MAP can be tested with a DMM that can test frequencies, and a vacuum gauge for reference.

More info here:

+1 for fuel pressure test. This is usually a good starting point to make sure that at least that vital is where it needs to be. If the fuel pressure if low, you will spend a ton of money on sensors only to find out you've been looking in the wrong place.

Best to start resolving hard faults (KOEO) and move on to the stored memory codes.


1987 Ford Ranger Short Bed 5.0L/T-5 Project
1988 Ford Ranger Long Bed Parts Truck
1993 Ford Tempo 2.3L OHV HSC Auto - D/D Stock.
1999 Honda Accord VTEC Auto
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