runs poorly in the rain or cold?

[OonDeanisS]

what would cause a 90 5.0 to stutter and pop under anything but full throttle when its not nice out? On sunny days it runs great once its warmed up. Any ideas would be great. It has new 02 sensors, fuel filter, good fuel pressure, good vac., 14* timing, new plugs wires cap & rotor, new IAC, new tps. thanks

 

[vristang]

Are you getting any diagnostic trouble codes?

There is a link in my sig, if needed.

Could be act/ect, but check the codes before making any purchases.


jason

 

[dragnazz5.0]

im thinking map/baro sensor but an act could possibly cause that also. also, try cleaning your maf. could be cooling off too much for the hot wire to read

 

[OonDeanisS]

i dont know what an act/ect is, nor a map/baro. sorry, no codes.

 

[HISSIN50]

Also check your grounds. I lived in Jason's city some time back and had some similar issues when it rained (350 days a year. ).

Good luck.

 

[vristang]

ACT - Air Charge Temperature sensor
ECT - Engine Coolant Temperature sensor
MAP - Manifold Air Pressure sensor
BP - Barometric Pressure sensor



EDIT:
What is your MAF / Injector setup?

 

[OonDeanisS]

24 lb injectors with i think a pro m 80, but im changing it to a new pro-m 75 and hopefully that will fix it. where are those sensors?

 

[OonDeanisS]

ttt

 

[jrichker]

ACT is located in the #5 intake runner on the stock 5.0 intake manifold.

ECT is located in the heater feed tubing on the RH front side of the engine

Map & Baro sensor -a 90 Mustang is Mass Air , so it only has a baro sensor. The baro sensor mounts on the firewall above the upper intake manifold.

Dumping the codes will normally show a faulty sensor. The ACT & ECT may be on the outer limits and not set a code but cause problems. Use a DVM or multimeter to check them.

Pin 25 ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.

Pin 7 ECT signal in. at 176 degrees F it should be .80 volts

The ACT & ECT have the same thermistor, so the table values are the same.

Here's the table: The values are +/- 15%, so don't get worried if your readings vary a little bit.

Voltages are measured across the two connector pins of the sensor with the sensor connected. Some safety pins used to probe the connector from the rear will be helpful.
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

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

 

[OonDeanisS]

i dont understand that

 

[HISSIN50]

Post specifically what aspect you don't understand. Otherwise, folks can end up typing for days and become frustrated with doing so.

Good luck.

 

[BadAndy]

spray water on the plugwires, see if it acts up

 

[jammer84_03]

if im not mistaken...isnt the 80mm just a little oversized for those 24# injectors?

 

[OonDeanisS]

hopefully because im waiting on a new 75

 

[OonDeanisS]

they are new plug wires

 

[OonDeanisS]

got the MAF today and it still bogs under anything but full throttle, unless its a warm day, then its great.

 

[TENGRAM]

previously, you said you have no codes...do you mean that you checked codes and got an 11 that signifies everything is ok...or that no codes at all were retrieved...or do you mean the CEL is not on? The check engine light won't come on for most problems, only the most extreme problems. it would be wise to Check for Codes, its free, very easy, and the only way to know whats really going on. let us know what codes you get

 

[90mustangGT]

Sounds like ignition issue to me. If the plugs, wires, cap, and rotor are new/good shape, I would really look at the module and pickup on the distributor. That's all it really could be. Except one thing, check the TPS voltage and do a sweep, be sure the voltage starts about .9V at closed throttle and goes up to about 4.5V at WOT. It should steadily go up. Any open spots (which will read 5V) or shorts (which will read 0V) you have a problem.

 

[Roland69]

does it blow out black smoke when it runs like crap

 

[OonDeanisS]

i ran the codes and the only one that came up was the fuel pump relay code, i dont remember which one it was.

it does not blow black smoke.

where is the module and pickup on the dist?

and i dont have a voltmeter nor do i know what doing a sweep is, sorry

thanks though