i have intermitent idle on my 1988 ford truck what could be the cause?

Question

sometimes idles to high it is fuel injected 5.0

Answer 1

first off suspect throttle position sensor. it should have a 5 volt [4.5 v is ok] reference and output at idle position should be less than 1 volt [0.85-0.96] is typical. at wot it should be close to reference voltage but never over [4.2v-4.7v]is ok the throttle body must be clean when idle readings are taken [no carbon present] i have found a lot of these have had the idle hard stop messed with by hacks and the only way to achieve less than 1 v is to unscrew the hard stop screw a turn or two [this invariably means that the egr valve is leaking by]. if this is the case the sensor on top of the valve and the vacume solenoid are also recommended [this is the solenoid with a red tube and a green tube going to it] the last thing to do is to clean out the constant idle motor, unbolt it and spray carb clean into it, shake it around and repeat until carb spray runs out clear and re install. then remove the ground cable from battery [negative cable]for 10 seconds [this will clear any codes and start a idle relearn process] these things should set your ford back to the good, be careful and neat about your work and no smoking around the carb cleaner. good luck

Answer 2

Engine lopes while idling or idles erratically;

1. Vaccuum leakage. Check the mounting bolts/nuts at the throttle body and intake manifold for tightness. Make sure all vaccuum hoses are connected and are in good shape.

2. Fault in the fuel or electrical systems

3. Leaking EGR valve or plugged PCV valve.

4. Air Filter clogged.

5. Fuel pump not delivering sufficient fuel to the injectors.

6. Leaking head gasket.

7. Camshaft lobes worn.

Answer 3

TPS= throttle position switch

Dirts throttle body

Dirty - blocked air cleaner (squirrels love to make nests in these 2 tube air filters.)

Or could be the fuel filter on the line or in the tank.

Also you have 2 fuel pumps on this truck - low pressure and high pressure.

Answer 4

try cleaning the IDLE AIR CONTROL valve

follow the intake from the air box and there will be a hose off that that goes to a valve and than a hose out that will go around the trottle body and into the intake

remove the hoses and clean with a good carb cleaner

Answer 5

I have to go with Kevrigger.It`s a 1988 truck.You probably need to change the fuel filter a lot for a while because you Gastank has all kind`s of deposits in it now if you have never changed it before.Vote for his answere please, if that helps.He just forgot to tell you why .

Answer 6

First, I would put injector cleaner in the tank. If that doesn't work, take it to the dealer and have him test the computer. Clogged fuel filters can also cause the problem.

Answer 7

Fuel filter

Answer 8

check your throttle plate......make sure the butterfly plate is clean & secure..............also check fuel pressure, and check for any vacuum leak,s.......try adding a good injector cleaner...change your fuel filter before testing fuel pressure....be prepared to change the fuel filter again soon after you add the fuel system cleaner........it will clean the tank&fuel line,s as well......all deposit,s end up in your filter....good luck!

Answer 9

is it tuned?..throw in a can of fuel injector cleaner [not carb cleaner] ...is check engine lite on..if so get a scan....other things....coolant temp sensor bad...throttle position sensor..oxygen sensor bad....then check fuel filter and pump.

Answer 10

Find the vacuum leak.