98 k1500 Hesitation

[zachary97]

Alright so I have a 98 with Vortec 350 and I have a bad Hesitation on Acceleration and at idle.if I’m sitting in Park at idle and I tap the gas pedal a Quarter Way down the rpms drop form 700 to around 400 And it will almost stall sometimes.I get some detonation Sometimes its worse in drive then park.now if I tap the gas to wot in park I get more detonation and sometimes it pops in the intake also sometimes if I’m backing out of a parking spot and Turing at the same time the truck will stall but fires right back up and if I’m driving and go wot it has a bad hesitation. Also I’ve had a few times where the rpms start going up and down at idle.so i did new plugs wires cap rotor and coil a few months ago no misfires no check engine light the fuel pressure was at 50psi at idle so I bought but a new Delphi fuel pump and filter put them In today still the same has new cats on it I’m thinking it’s the Injectors because if I take the intake tube off and open the Throttle I can smell gas in the intake but idk.any ideas what it is?

 

[kennythewelder]

You need to do a code read. A live date read is a lot better than a non live read. It sounds like ignition issues but without a code read or being there to run some test, its hard to say. It could also be leaking injectors and several other things. Without more info, its hard to say.

 

[zachary97]

You need to do a code read. A live date read is a lot better than a non live read. It sounds like ignition issues but without a code read or being there to run some test, its hard to say. It could also be leaking injectors and several other things. Without more info, its hard to say.

What kind of tool would I need for that I don’t have any scan tools right now

 

[kennythewelder]

What kind of tool would I need for that I don’t have any scan tools right now

There are a ton of them out there. The bluetooth tools ate nice, and you kind of get what you pay for. As for a brand, well I bought a Jet prigramer years ago that does live data reads, so I use it, but it was around $325. The code readers are much less. You can pull of the throttle body and look inside the intake with a mirror and a flash light to see if there is a fuel leak though. You will need to jump the fuel pump relay so that the fuel pump will run without the starting the engine. Here is a video that tells you how to do that.

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[delta_p]

How long since the mass airflow sensor has been cleaned? Does it run right at all if you unplug the MAF and run open loop with it?

 

[zachary97]

How long since the mass airflow sensor has been cleaned? Does it run right at all if you unplug the MAF and run open loop with it?

The mass was replaced about 8 months ago looks clean on the inside.but has no affect if it’s unplugged still does it

 

[zachary97]

There are a ton of them out there. The bluetooth tools ate nice, and you kind of get what you pay for. As for a brand, well I bought a Jet prigramer years ago that does live data reads, so I use it, but it was around $325. The code readers are much less. You can pull of the throttle body and look inside the intake with a mirror and a flash light to see if there is a fuel leak though. You will need to jump the fuel pump relay so that the fuel pump will run without the starting the engine. Here is a video that tells you how to do that.

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I thought about buying a GM tech 2 but idk with the jet do I need a laptop because I don’t have one

 

[kennythewelder]

I thought about buying a GM tech 2 but idk with the jet do I need a laptop because I don’t have one

Although the Jet CD are better, they do offer a hand held flash tuner, or did when I got mine anyway. Its ok, not the best, and not the worst. I wanted to did the high performance tune on mine, and was a little disappointed. I though it would do a lot more to pep up the truck than it did, but it really helped out the trans. It shifts a lot crisper and sharper than before. I did gain some engine performance, dont get me wrong, but I though it would do a lot more. With all my mods ( I have not gone any deeper inside the engine than the intake) Im around 325 HP. Not bad when you consider the engine OE was only 265 or so. From what I understand the GM tech 2 is a good choice.

 

[zachary97]

Although the Jet CD are better, they do offer a hand held flash tuner, or did when I got mine anyway. Its ok, not the best, and not the worst. I wanted to did the high performance tune on mine, and was a little disappointed. I though it would do a lot more to pep up the truck than it did, but it really helped out the trans. It shifts a lot crisper and sharper than before. I did gain some engine performance, dont get me wrong, but I though it would do a lot more. With all my mods ( I have not gone any deeper inside the engine than the intake) Im around 325 HP. Not bad when you consider the engine OE was only 265 or so. From what I understand the GM tech 2 is a good choice.

I haven’t done any mods to the truck yet but for the moment trying to fix it so it won’t stall when I’m pulling in to traffic that’s no fun if I gain some pony’s that’s fine with me lol

 

[Schurkey]

You need to do a code read. A live date read is a lot better than a non live read.

A "code reader" is not a "scan tool". A scan tool gives you access to the data stream--which is arguably MORE important than the "codes"; especially if the MIL is not lit.

It sounds like ignition issues but without a code read or being there to run some test, its hard to say. It could also be leaking injectors and several other things. Without more info, its hard to say.

Very true. If fuel pressure, and cranking compression are OK, the answer is in the data stream.