Running like crap

[Blockbeata09]

OK guys I have a 97 k1500 305 and I replaced the TPS and map sensors yesterday and my truck is running really rough. Could replacing them throw off the timing? I need help cause I'm already dumped way too much $ in this truck to get it running correctly and can't. Thank you.

 

[magimerlin]

No they can not mess up the timing... is your check engine light on??

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[Breakdown]

Why did you replace the sensors first. Quick way to test the TPS is with a analog multimeter, hook it up to the plug and have someone slowly operate the throttle from none to full. watch the multimeter. if it moves cleanly and doesnt jump around thats most likely not your problem. not sure on the testing regimine for a map sensor though.. being its a 97, these things were NOTORIOUS for intake manifold gasket failures causing rough running, and they are not hard to change

 

[Blockbeata09]

Well when I was going down the highway and let off the gas the truck would begin to studder but I give it gas and it would go away or if I used cruise control and went down a hill it would do it also and check engine light would come on and say random misfire on multiple cylinders. I replaced the crankshaft sensor and it stopped doing that but it kinda wanted to studder taking off from a stop so I was told the map or tps sensor could be causing it so I replaced both. I'm lost on what to do.

 

[east302]

I would start with a spark test for each wire to check for ignition problems.

If that checks out, a fuel pressure test and compression test would be next.

How long has the fuel filter been on?

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[Blockbeata09]

I would start with a spark test for each wire to check for ignition problems.

If that checks out, a fuel pressure test and compression test would be next.

How long has the fuel filter been on?

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I put new oem plugs, expensive plug wires, MSD distributor, ignition coil. I have a new fuel filter and pump and had them check the fuel pressure also the other day.

 

[Blockbeata09]

I'm just going to put the stock map back in reset the PCM and see which sensor is causing it

 

[magimerlin]

You say a new coil aswell.. was it a stock one or an msd like the distributor? Alot of people on here had issues with using the msd coils on our trucks... they got a stock replacement and all was well again....

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[Breakdown]

You say a new coil aswell.. was it a stock one or an msd like the distributor? Alot of people on here had issues with using the msd coils on our trucks... they got a stock replacement and all was well again....

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Funny thing about that, the pre-vortec engines worked great with the MSD coils, Vortec's and LS hate them... figure that one out....

 

[east302]

Was the misfire code P0300?

Was the relearn procedure run after the crankshaft position sensor was replaced?

After the distributor replacement, was the cmp retard adjusted (0 degrees +/- 2 at 1000-1200 rpm)?

How does the rubber seal on the MAP sensor look? Wondering if you could have a vacuum leak or leaking EGR valve--I think you'd need a scan tool to verify if it is functioning correctly.

Are you losing coolant (lower intake gasket leak)?


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