my truck surges at idle and stalls. Also it will slowly stall if i just hold the accelerate, at say, 2500 rpm. BEFORE this issue started i have replaced the following last month as a tune up EGR valve PCV valve K&n filter royal purple oil MSD coil accel cap/rotor AFTER this issue started i replaced: MAP sensor IAC sensor new plugs new fuel filter new fuel pump still the same issue. Im at a total loss right now. any ideas? EDIT: also forgot to add i replaced the TPS sensor

0) Check your alternator voltage - should be 13.8 and above! 1) Check Fuel Pressure - even though you have new fuel pump it is no guarantee that fuel pressure is maintained at 13 PSI. 2) Check ignition components. It is not unusual to have a flaky ICM (inside dizzy). Make sure that that it is properly grounded and that reluctor coil is correctly plugged in. MSD coil may require additional current on primary windings which stock (or tired) ICM may not be able to switch. Check that ignition coil primary windings supply voltage (#10 AWG pink or red wire) - is rock steady at about 13.8 volts. 3) Check spark plug firing order - it is all too common to swap couple cylinders around. Post what you find... //RF

i should also add, that this problem all of a sudden just started out of NOWHERE. i was driving casually and it was a warm sunny day and it just started all of a sudden.

thank you for the response, i will try what you reccomended.

how do i test these componets if my truck wont idle long enough?

TigerZ

1) If you still have your OE coil swap it in for now. Aftermarket coils tend to draw higher current (thats how they achieve higher spark plug voltages) through their primary windings. Stock engine with 0.035 gap does not really need 50kV coil - stock 25 to 30 KV is adequate. Pull # 1cylinder plug and connect in line spark tester. You can see how hot spark is, or if there is occasional miss.

2) Checking spark plug wire routing on a quasi idling engine is asking for it.

3) ICM module can be removed from dizzy - better autoparts stores have testers. Do not expect major chains to have one, or the clerk behind counter able to operate one correctly. You may need to get one spare - get Delco or GM unit even though it's a bit more expensive. Over the years I have accumulated a few of these pesky parts during swaps and troubleshooting sessions.


4) Fuel pressure test does not require running engine. Once you connect inline FP tester you can force FP to operate by energizing FP relay pigtale if there is one, or otherwise forcing FP relay to stay energized.

In your case it is either fuel delivery is flaky or ignition side is acting up.

//RF

This happened to my car recently. it turned out to the the Coolant Temp Sensor. Something about the car not knowing the temp when cold and throwing in to much fuel or air. Pulled it off and screwed in a new one and it worked just fine.

alright, ill try that tomorrow.

A dead CTS will throw code (SES light will start flashing). Code 14 if sensor voltage is low - very high temperature, Code 15 if sensor voltage is high - very low temperature. The easy check - cold engine, disconnect CTS and measure sensor resistance. At 72 degree ambient DVM should read 2.6 to 2.7 kOhms.

//RF

yeah i checked that sensor its fine.

i dont know what i should do
i dont have a timing light or Fuel pressure tester, and no place rents them out.

http://www.youtube.com/watch?v=tkVWMqWEWys

TigerZ

Watched your utube video. I am kinda scratching my head but two things that stand out:

1) Engine is starving for fuel. I know that you've changed FP and filter - check for pinched line or kinked fuel line somewhere. It is possible that you may have a defective replacement pump or a lousy electrical connection causing pump to run slower.

2) Low Alternator voltage. Can you at least check make sure that your alternator is supplying charging current. It should put 13.8V + at 2000 RPM

Ignition sounds like it is OK (from video). I'll check later tonight.

//RF

i just checked the terminals at the battery with the car on and off.
OFF it was around 13

ON it was around 12

this is really wierd. why would i have a higher voltage with the car off. and if it was my alternator why would i be able to start my car so many times like i have.

Hmmmm - how did you measure voltage - right across battery terminal??? Under normal circumstances, with engine running, voltage should be closer to about 13.8V. However your truck is equipped with Delco-Remy CS130 alternator. CS-130, which denotes 130mm case diameter came in 85/100/105 Amp ratings and unlike its SI predecessor this alternator uses a switching field current regulator. Regulator switches field windings current on and off at a fixed switching frequency of about 400 cycles. By varying the duty cycle required average field current for a set output voltage is obtained. At high RPM the duty cycle may be 10% and at low engine speeds and high electrical load duty cycle can be increase to 90%. The biggest headache with CS-130D self regulation is it builds up tons of heat, gets too hot and stops charging until it cools down.

Enough of background info - check alternator output at the alternator BAT terminal. You maybe running on battery and dying alternator.

//RF

i just got back from autozone, had my alternator bench tested. passed every single one.

Hmmm and the mystery is getting deeper! OK, so it checks out OK. Do you get 14 volts at the alternator output terminal (labeled BAT)?

//RF

just replaced fuel pressure regulator

same issue

my coolant is gone, and have a a cold cylinder that is getting spark.



****

i just did the compression check
im getting some weird readings

Cyl.1 = 179
cyl.2 = 187
cyl.3 = 175
cyl.4 = 188
cyl.5 = 185
cyl.6 = 170
cyl.7 = 172
cyl.8 = 183

cyl. 2 is the cold cylinder

i still cant explain my massive coolant loss

i read through my haynes manual and it says normal compression is 150 PSI. so im wondering if my tester is bad.

i just drained the oil and didnt really have any evidence of coolant.
however when i was running tests i remember seeing some white smoke come out of the intake through the carb. i probably have run the motor about an hour since the actual incident. so im starting to think maybe i compressed and burnt the coolant out.

i just pulled off the valve cover of that cylinder and all the springs are good. all the rockers are tight. it looks very clean in there.

just heard back from the shop


timing chain broke.

$700

and in order to get the.

cover off they're gonna have to remove my oil pan gasket


shitty

Aghhhh - thats a real bummer. I had rice burners pop timing belt on me but a timing chain??? Unless original timing gear was made out of plastic!!

//RF

Pardon my ignorance but how can it run at all without a chain to move the valves?

i spoke with the mechanic again, i misheard him, the timing chain was really worn down and had a lot of slack in it, wasnt broken. Also my spark wires were arching off my manifold. the reason this is so expensive is on my truck the oil pan has to be removed to access the timing chain, so the oil pan gasket needs to be replaced as well due to its age.

Timing chian, wires, new oil pan gasket, and labor the estimate was $700.

cant wait to have it back

this will also fix my oil leak

Hey Tiger

Nice! - I that a metal gear??? Back in my college days I had a '76 Malibu with 305 that GM back in disco days equipped with a plastic gear to reduce drive train noise. Needless to say it went out in a middle of I-5, in central valley, in a middle of nowhere. I was paying that CC bill for about 10 month <;().....

//RF