86 Cimarron lean, hesitation, poor fuel mileage, loud - First Generation Forum

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86 Cimarron lean, hesitation, poor fuel mileage, loud
Thursday, March 14, 2013 6:25 PM
Hi there. I'm waiting to receive a shop manual in the mail that should help with some of this stuff but for now I have to bother you all

A little background on the car. It is a 1986 Cimarron with 67000 or so actual miles. It was driven rarely throughout it's life by an older farming couple and was sold a few years ago to a younger guy who only drove it occasionally and it sat for long periods between.

It has had regular oil changes and such but no major repairs.

I haven't had too much chance to diagnose problems and I'm terrible at it anyway so I thought you all might be able to help.

Anyhow the symptoms are poor fuel mileage (used half a tank in about 90 miles), plugs are chalky white throughout (not blistered or chunky white though), it idles high both in gear and in park, it hesitates when accelerating from a stop, and it's still pretty loud even after fixing the exhaust. It doesn't look like the coolant has any oil in it and the exhaust doesn't smell that wierd, but there is some exhaust smell in the cabin even after fixing the exhaust. A few times on a very cold morning it will sound like it is missing on a cylinder until it warms up and then it is fine.

I'm not sure what to look for in a tbi setup but with the air cleaner cover removed it looks like quite a bit of fuel on the throttle plate at idle.

Any ideas on what I should check? I'm going to try new plugs, try to test the compression, and maybe a new fuel filter tomorrow.

Could it possibly be bad gas from having sat?



Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Thursday, March 14, 2013 9:26 PM
First is how long that gas sat.IF you burned 1/2 tank your doing good to get it well gone.Things I would do are new plugs,new wires,new distributor cap,new rotor, change the oil and filter bc your getting fuel in the oil burning SO rich.Do the filter yes,but remove the EGR and clean it with carb cleaner and toothbrush to remove the carbon buildup.Now to me your TBI probably needs a simple rebuild like new injector,new harness to injector(only if junky) just a rebuild kit and in that kit it will have a new diaphram for the fuel pressure regulator.I would also replace the oxygen sensor.I would not replace the map sensor on the firewall or check that yet.And no bother on tps yet.I might suggest removing the IAC(idle air control) but,let's do a good tune up,rebuild that tbi bc that time sitting and age deterioates the things internally.Keep it simple at first and if after the things I suggested clean it up and still some mild things we will focus on the map sensor,tps and may even suggest replacing your temperature sender this matters alot bc it affects how the car runs at certain temps based on the ECM controlling things.While doing the tune up check the vacumm lines ALL of them for wear,cracks,brittle and there are not that many really.Also do a new pcv valve.If I forgot something may others chime in and add or correct me.I also assume you have a 4 cylinder right?I just wrote a small book and just know I will say later (crap I forgot something).



Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Thursday, March 14, 2013 9:37 PM
thanks so much for the suggestions, ill get to work on that stuff and report back. also i should note that my temp gauge is wonky. sometimes it kind of swings wildy around but sometimes it just stays pegged at hot. if it were overheating i would get an idiot light wouldnt i? i thought it was the gauge but it might be the temp sensor. do you happen to know if there are one or two temp sensors?


Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Thursday, March 14, 2013 9:51 PM
Please indicate 4 cylinder or 6.Now that you said the above IF the coolant sensor is bad,OR has a bad connection this will make the car run like(@#%&).To answer your ? yes if the real temp was pegged it should kick the warning on the dash.But being the gauge wanders from normal to out of limits says to me you probably have a bad water temp sender and or it has a crappy connection(like corrosion or not tight on the sender).Even though you have a true water temp gauge it should have the idiot light for coolant in thought.I would just replace your water temp sender 1st!!!! then see if the car runs better.If so I still would do a mild tune up so you know things are up to date,and not run into issues wks,months later.Just sitting kills stuff if not run routinely and it will crap out.The temp sender affects how the cars ECM controls the fuel,air,idle just general running.Simple it sounds but super 80's technology is wayyyy out there.



Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Thursday, March 14, 2013 10:47 PM
its a 4 cylinder. do you need to know that to tell how many sensors i need? since the injector, throttle body rebuild kit, and coolant temp sensor/s will run up over 100 ill wait on the o2 and spark eqipment. advance has a 30 dollar coupon for spending over 75 so ill do that stuff with the coupon. i can check the plug wires at least with a multimeter. ill order up the rebuild kit though and the sensors.


Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Friday, March 15, 2013 4:47 PM
gah. i was thinking for some reason that it needed one sensor for the gauge and one for the ecu. my bad.


Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Sunday, March 17, 2013 7:37 AM
gotta love those advance coupons - google them. I found one for $40 off anything over $120 or something like that. Make your own sale!




Re: 86 Cimarron lean, hesitation, poor fuel mileage, loud
Sunday, March 17, 2013 7:35 PM
On my 87 Sunbird TBI 2.0 there are 2 sensors which relate to the coolant. The sensor in the block under my distributor has a single green wire to it and it is the sending unit for my temperature gauge. I just got that sensor from Advance today. It cost $11.59, but I took them a used battery that was given to me and got a $5 credit so the sensor was much cheaper. That fixed my gauge issue.

The sensor in my filler neck under the radiator cap has two wires to it and it sends the water temperature information to the ECU or computer. That sensor also helps to control the electric fan when the car is 230 degrees. My Snap On scan tool shows me the temp much faster than the car gauge. If that sensor was bad, I think the scan tool would not know what temperature the engine coolant was, and my fan would not work, but those things worked in my case when I ran the car to get it hot to test the gauge sending unit I had just installed.

I hope that bit of information is helpful and insightful.


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