please please help

302mustanglx · Jul 8, 2011

okay guys im the end of the road after loveing this car im at the point were i whant to sell. The isue im having with it is iradikal idleling when i try to time it timing mark moves back and fourth dosent stay in one place so i can get a acurate seting. When i get it to drive with out staling it buckles like crazy it seems like it puddles up with fuel and dosent go nowhere. it just dosent seem to idle right in order for it idle without surging i have turn the idle screw were it idles at 1500 rpm witch is to high.What ive done to fix it is put a new mac maf 76mm cal for 19 pound injectors new msd dizzy fuel presure is at 40psi with vacum conneted.Car has no smog what so ever just bearly got done being rebuild. Also i did pull codes when car is off and i got code 51 code 31 and others that end up being smog equipment.I also notice that the tps may be reading i poked a hole trew it to check the voltage and its geting preaty bad to a point were few cABLES HOLD IT TOGETHER COULD THAT BE A ISUE WHY IS DOING ALL THIS.

Rick 91GT · Jul 9, 2011

Id fix the TPS, but if the timing is jumping around Id assume you do not have the spout connector out? Pull the spout connector (little grey or black block right near the distributor) out to set the timing then, re-install after your done.

Set Fuel Pressure to 38psi VAC OFF!

90stang5speed · Jul 9, 2011

What Rick said plus, here is an issue I had with mine. When I first got the car, the timing jumped around a little even with the SPOUT out. Later it blew a head gasket so I took that time to upgrade to the Explorer intake F303 cam & while doing the cam, I put in a new timing chain & gears. My old chain was really sloppy & after changing the timing set & putting everything back together, the timing didnt jump around anymore. Make sure you go through the surging idle check list also. Once you get it to run better, I would set the idle screw back too. From what I understand, you should unplug the SPOUT & the IAC. Then ture the screw back out until the car can hardly run (about 500 RPM). Then when you plug in the SPOUT & IAC, the computer will bring the idle back up to where it should be. Check for vacuum leaks too. when I had the explorer intake, one of the metal tubes on the underside of the upper intake cracked loose & cause a major vacuum leak for me. hope that helps.

BlackGT89 · Jul 9, 2011

Yeah, if you had your spout connector removed and the timing still jumps around there is a good chance your timing chain is shot and has a lot of slack in it. Somewhere there is a procedure for checking that amount of slack that is allowed.

This is pretty general but maybe it will help:
http://www.misterfixit.com/chanslop.htm

302mustanglx · Jul 9, 2011

ok i will go ahead and change the tps but i did have the spout of when i was timing the car i had the car of remove the spout and try to set it back at stock ten degrees it dosent stay on it dies really bad surging.It whants to idle fine like at 28 to 30 degrees witch is to high guys. il turn the fuel down to 38 with vacum off like u guys say.Another thing like i wrote it has just been rebuild and a aftermarket timing chain has been put in it.I will check for vacumleacks like u said and see what i find

302mustanglx · Jul 9, 2011

My timing chain is one of those that can retard or advance its retarded 4 degrees. I dout that has to do anything with the way its acting or does it.

jrichker · Jul 9, 2011

Fix the codes first.The code fixes and definitions are below. Once the codes are fixed, if you stll have problems, See the "Surging Idle Checklist for help with all your idle/stall problems.

The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
Possible bad ECT sensor, or wiring. Possible missing signal ground –
black/wire wire broken or bad connection. With the power off, measure the
resistance between the black/white wire and battery ground. You should see
less than 1 ohm. Check the same black /white wire on the TPS and MAP
sensor. More than 1 ohm there and the wire is probably broken in the harness
between the engine and the computer. The 10 pin connectors pass the
black/white wire back to the computer, and can cause problems.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Voltages may be measured across the ECT by probing the connector from the rear.
Use care in doing it so that you don't damage the wiring or connector.

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections.

Diagram courtesy of Tmoss & Stang&2birds

302mustanglx · Jul 9, 2011

ok so what u sayint i shoul just try to dump the codes

BlackGT89 · Jul 9, 2011

So it sounds like you have an adjustable timing chain, is it a Hex-A-Just ? If it's an aftermarket chain it probably doesn't have that many miles on it to cause it to be stretched. I'm not familiar with those but I assume they have some kind of lock down on them. Maybe the lock down has worked it's way loose or something ?

I had an '83 T-Bird 5.0 (non-HO), but when the timing chain went out on it, when I would punch it, it would really lay down on me, lots of bucking and sputtering. If I eased into it it ran decent, but still had no power. Of course check the codes first as recommended, that's a lot easier...

jrichker · Jul 10, 2011

302mustanglx said:
ok so what u sayint i shoul just try to dump the codes

Fix the known codes first. The code descriptions I posted will help you do that.

Once they are fixed, see the "Surging Idle Checklist for help with all your idle/stall problems. You are not the first person to have idle/stall problems and the"Surging Idle Checklist is designed to help you find and fix the problems

302mustanglx · Jul 12, 2011

ok buddy i fix the codes that were on it exceps the cooling sensor im just gona replace it this friday. seem to be runing good set the tps at 98 fuel at 38 psi with vacuem off whent for a spin was runnig ok felt like i could add more timing whent and did a burnout 4 like 30 sec afte that its stared runing a bit hesitaty full power wasent there it got shacky again buckeling pull the codes again and now i got cod 98 what gives is that why is runing like that.

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