94 ranger flat spot
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94 ranger flat spot
Ok I posted this in the 4 banger forums but there is more people here so Im gonna try again. Alright so I have a 94 ranger 2.3l manual that has a flat spot around 2k rpms. The truck will accelerate fine most of the time but every once in a while around 2k-3k rpms it will hit a spot where it will I guess bog the engine and slow down then get back on the power and run like normal. I have noticed that it will usually do this back to back like 2-4 times then stop and run ok for a few minutes then do it again. Does anyone know what this could be. It seems that it only happens when the truck was cold but lately I have noticed it when the truck was warm also. Any info would be helpful. Thanks in advance
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From: ut
When I bought my 94 last summer (4.0L) it was doing something similar. No CEL light either. I ran a koeo and koer test and found a throttle position sensor bad. As Rockledge said, I would suggest cleaning the MAF sensor, and performing basic tune-up stuff too. If you think it's temperature related, check your ACT and ECT sensors also.
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Well it has a new maf sensor thats less than a year old and I know I have cleaned it like 3 months ago. I guess I can check that. Also I have been paying attention to it and it only seems to really happen when the truck is cold. Once it warms up it will happen like 10% of the time compared to when its cold. This is the only reason Im kinda thinking its not the TPS. If this was the problem wouldnt it always affect the truck. I will run a KOEO and KOER today to see if I get any codes. Thanks for the help
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From: ut
You're probably right that the TPS would always affect the truck regardless if its warm or cold, but it's hard to say if this is always the case. The KOEO and KOER test should show a fault if there is one. There's other possibilities...I've heard of loose intake manifold bolts (upper and lower) that will give you a vacuum leak until the engine warms up. Might pay to look at those too...easy stuff that shouldn't take too long to check out. I think your ECT should read about 58,000 ohms with the antifreeze about 50 degrees F. If it's warmer the resistance goes lower, about 1000 ohms at 250 degrees....Just another quick check.
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From: ut
...also, read a post on another forum where the fix for a similar problem was replacing the plug wires, he'd already replaced the plugs.
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ok so I checked the KOEO and KOER today and they both gave a code 116 which says the engine temp sensor is out of self test range. I have already replaced the engine temp sensor once before like 1-2 years ago but do you think it could have gone bad after I accidently let my engie overheat. I put on an electric fan thats run by a switch for right now b/c I had the problem with my truck running to cold. Do you think that could ruin the switch. I also did a cylinder balance check and that was fine. I am going to check the plugs tomorrow but does anyone know if the temp sensor was broke if it could make the truck have these flat spots. Thanks for the help
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oh I also forgot to add that my truck has become harder and harder to start. Sometimes it takes me like a minute to get it started and when it does it shakes like crazy almost like the engines out of balance b/c its only running on 3 cylinders but after 5-10secs it clears up. Hopefully all these problems are related. Thanks for the help again
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From: ut
The KOEO test is called an "on demand" test. It gives hard, or current, real-time faults...faults as they are right now with the engine off. The KOER test, or "continuous fault" test shows faults that have occurred the last time the engine ran, or earlier. If you have the same fault on both, then there is a definite failure in that circuit, either in the sensor or the wiring. Do a resistance check on the sensor. If it's in the proper range, then refer to the wiring diagram for your truck. Pull the connector off the computer, and do a resistance check on the two wires going to the sensor. The readings should be almost identical. If not, you have a wiring problem.
As a side note, I understand that on start-up, the computer looks only at the ECT sensor during cranking for timing and injector pulse info. If that circuit has failed, you may get weird stuff happening on start-up.
As a side note, I understand that on start-up, the computer looks only at the ECT sensor during cranking for timing and injector pulse info. If that circuit has failed, you may get weird stuff happening on start-up.
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Ok thanks Im starting to think that it must be the ECT or the wiring thats giving all these problems. I am def. gonna check that out tomorrow and hopefully thats it. This wouldnt throw the check engine light though if the wiring was bad?
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From: ut
oops...I gave some false info...The KOEO test gives BOTH "on demand" and "continuous" codes. The current real-time faults are given first, then a 5 or 6 second pause, then a single seperator code pulse, then another 5 or 6 second pause, then the continuous, or memory codes are given. Sorry for the false info....
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ok I changed the ect sensor out b/c the other one was all messed. When the engine was at about 80degrees the sensor was reading that it was like 250degrees so Im pretty sure that was the problem. It starts fine now but I havent driven it since im now getting ready for a superbowl party 
. Thanks to everyone who helped. Also I was wondering if anyone knows of something that can be put on my truck to turn on the electric fan I have installed. Right now I have a switch and always planned on finding something to do this but just havent. Anyone know if a coolant switch from another car or another year ranger would work to do this. Thanks again for all the help.
. Thanks to everyone who helped. Also I was wondering if anyone knows of something that can be put on my truck to turn on the electric fan I have installed. Right now I have a switch and always planned on finding something to do this but just havent. Anyone know if a coolant switch from another car or another year ranger would work to do this. Thanks again for all the help.