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Discussion Starter #1
So i have a 97 k3500 5.7l, we bought it for towing our holiday trailer and from the first time i towed it seemed to be lacking power. (I will try and give as much info as i can to make it easier for everyone). Before i even hooked up to the trailer a friend convinced me to have the computer reprogramed for better milage and more power, so i did. Could not relay feel a difference around town, then we hooked up our trailer (4100lb dry and 7500lb loaded) for the first time and man was it ever gutless. I had more power with my dads 02 5.3l and my old 90 k1500 5.0l. The truck drank fuel and had zero power when we got to some bigger hills, on the flat and small inclines was tolerable but anything bigger or a head wind, it was junk. The truck sports a 5.7l with about 150000km (sorry dont know what it is in Miles), 4L80e trans, 4.10 gears, HD frame, air bags in the rear for extra help, 3 trans coolers (1 good for 28000 lbs), k&n air filter with the top of the air box removed for more flow, both of the cats have been gutted and no check engine light. I have changed the plugs, fuel filter, cap, roter, pcv valve and cleaned the air filter, can some sea foam throught a couple tanks of gas and one can was sucked through a vacuum line, engine shut off and then started again 25 mins later to clean up any carbon. Compression tested 180psi on 7 out of 8 clys and 185 on the other. The problem is almost non existent with no trailer, but still at highway speeds seems a bit lacking.

Other thinks i have tried...
-Towing the trailer with it unplugged thinking it was the breaks hanging up. Problem still there
-Driving in a lower gear to keep the RPM's up. Still there
-Tried with everything shut off, A/C, fan, radio, etc. Still there.

It is getting a bit frustrating. We are going to the Oregon coats for 2 weeks in Aug and i want to figure this problem out before then so i can enjoy the drive and my vacation. I realize that this is not a Diesel or a 454, but like i said before i used to have an old 90 5.0l and towed a 6000lb race car trailer every weekend with no issues.

Can anyone help my out or give me some pointers or suggestions.

Thanks in advance and sorry for the long post.

Steve
 

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I'm guessing that when they reprogrammed the computer they favored the MPG & this has hurt your power.
Since you suspected the trailer brakes hanging & disconnected the electrical to test, I'd go another step & jack up the trailer & spin the wheels. They could be dragging from mechanical issues rather than a bad electrical controller.
You have good compression on your 5.7 L & with 4:10 gears should pull 7500 lbs fairly decent. Mine dogs out on really steep hills pulling my boat & trailer also 7500 lbs. (down to 40-45 mph) but not unusual for this amount of weight imo.
 

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Alright well i will start off with a couple of questions.. please dont take an offense. What type of plugs did you put into the motor? And i agree with Stephan that they went the wrong way with the tune, and have you running for better milage which is killing your towing ability. Do you still have a muffler installed? Because a lack of back pressure from the gutted cats (if you dont have a muffler) you wont have the power that you need.
Also i agree to take a look and make sure there isnt anything dragging on the trailer axles. And with "roughly" 92K miles that motor is like brand new for the most part.
 

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Discussion Starter #4
Thanks Stepan and Murdog for your quick replys.

I have not checked the drag on the trailer, but i am guessing because i recently used my dads truck to move the trailer and had no problems. As for the plugs i have NGK plugs from NAPA. I just told them the truck and they said these are the ones. I do have a muffler on the truck. Would it be worth it to buy a programer with multiple setting on it, tow/millage/performance/etc? I am going to check fuel pressure this week but i think it is ok as the truck is not bad with no load. I was also leaning towards the computer being too lean for milage.
 

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The plugs are the wrong ones for the motor, and actually NGKs are about the worst ones to run (other than those stupid E3 things) that can cause a loss of power... Running AC delco Platinums is a good idea since the NGKs might last 4K miles but start to screw up and then you are stranded.
Now for the programmer yes it would be a much better idea to get a good multiprogram programmer. Alot of shops that do "custom tuning" dont necessarly do the best job of it.
 

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The plugs are the wrong ones for the motor, and actually NGKs are about the worst ones to run (other than those stupid E3 things) that can cause a loss of power... Running AC delco Platinums is a good idea since the NGKs might last 4K miles but start to screw up and then you are stranded.
Now for the programmer yes it would be a much better idea to get a good multiprogram programmer. Alot of shops that do "custom tuning" dont necessarly do the best job of it.
X2....On the NGK's being the Wrong Plugs and also as mentioned by Murdog94....you want A/C Delco Platinum Plugs....the Vortec Engine's Run & Perform Best When A/C Plugs are being installed.
 

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Discussion Starter #7
I will get some new plugs first thing monday, will old plug wires do the same thing?

As for the programer which one is recommended? I am looking for more towing than anything.

Steve
 

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Old wires can cause a misfire.... As to a programmer if you search the site some you will see what others have used and what they prefer...
 

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On the A/C Delco Plugs are Gaped during Manufacturing, which for the Platinum Plugs is set at....0.60, Check the Gap to make sure they are Gaped Correctly, but Do Not Attempt to re-gap them as the Platinum Tips Can be Easily Damaged.



SPARK PLUG ASM

Part Number: 41-993
Product Notes:

Platinum Spark Plug

.060 GAP

Per Vehicle: 8; Years: 1996-1998​
 

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Don't forget to check the air intake tubing for restrictions. I've seen birds and mice build some pretty impressive nests in them and cause all kinds of problems. It's easy to overlook. Be sure to take it loose at all the connections so you can clear out the entire thing. By the way, I second the opinions on AC plugs.
Good Luck and God Bless
 

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The plugs are the wrong ones for the motor, and actually NGKs are about the worst ones to run (other than those stupid E3 things) that can cause a loss of power... Running AC delco Platinums is a good idea since the NGKs might last 4K miles but start to screw up and then you are stranded.
Now for the programmer yes it would be a much better idea to get a good multiprogram programmer. Alot of shops that do "custom tuning" dont necessarly do the best job of it.
X2....On the NGK's being the Wrong Plugs and also as mentioned by Murdog94....you want A/C Delco Platinum Plugs....the Vortec Engine's Run & Perform Best When A/C Plugs are being installed.
Ok heres my question. I dont know if it was the new set of AC Delcos that I bought or the stock ones I pulled off (I'll check that later), but on one side of the plug it said AC Delco and on the other side it said NGK (not trying to hijack the thread just wondering if anyone else has seen that). Only reason I remembered was because I thought it was very strange.
 

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On those plugs it was most likely a part number or something along those lines and they were NGK, the delcos have the part number and AC written on them.
 

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yep its got both. On on side it says ACDelco 12567759 and turn it and it says NGK PZTR5A-15 (these were the stockers). this was a double platinum so obviously they went to iridium which was AC 41-985 discontinued and now AC 41-110. So who actually made the stock plug NGK or AC Delco
IMG00209-20110711-1832.jpg IMG00210-20110711-1833.jpg
 

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I would bet AC
 

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Discussion Starter #15
So a quick update. I checked the plugs and they are AC, called the dealer with the number on them and was told they are the right ones. Made a couple calls about the programmer, was told the Hypertech was the best for my year and engine, one place said $368 and the other said $650. WOW quite a difference, now this one is supposed to be 25HP and 50TQ. I also got a price on a JET Performance one, was told 130HP and 205TQ for $528, i have a hard time believing that it can give me another 200f/lb of TQ, anyways.....Also the first guy i talked to was real helpful, he asked if i was having any problems or was just looking for more power, i explained to him my problem and told him about the dude re programing my computer already, he told me that with the Hypertech it is a must you run premium fuel or you will get pre detonation (pinging) and the knock sensor will detect and retard the timing, taking all the added power away. He told me to try a tank of premium fuel first before running out to buy the programmer. What is everyones opinion on all of this.

I am also curious to know if anyone has ever used the Jet programer and if the numbers are what they claim they are.
 

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I'm not sure on the jet programmer and those numbers, but for the prices that you are showing you can get a custom tune for around the same price and get it set for 87 octane. wait4meperformance.com (look up heavychevy on here), blackbear tune (I believe jennabear on here does that one) are 2 that have gotten alot of praise on here. wait4me puts 3 custom tunes on a handheld and blackbear is a PCM swap. Also for an over the counter tune the diablos come highly rated on here.

And I forgot to say earlier that I agree they tuned it for mileage and it killed the power and that AC Delco's are the only plugs to put in here.
 

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Discussion Starter #17
The latest....Went camping last weekend and was feeling something funny in the trans. When we got to the camp site i had a buddy go for a ride with me to feel what i was feeling, he said it was feeling like the trans was going, so i took it easy as i needed to get the trailer and truck home. As i was backing up to the trailer to hook up at the end of the weekend, it was a slight incline 20 feet long and 1 foot of incline, i was not able to back up unless it was full throttle. Finally got to the trailer and hooked up and away we go. Babied it home and called around to a few transmission shops for some pricing. More than what we wanted to spend, right around 3 grand. Dropped it off on tuesday and now thursday night and it is ready. The guy at the shop said that reverse clutches were gone, high gear was gone, and first and second were less than 10% remaining, the torque converter was plugged up with crap and the lock up was only working 50%. He told me that we was surprised i was able to drive it in. I told him about the power problem and he said it was probably the transmission and converter that was robbing all of my power. I will pick up the truck friday and will grab the trailer and give everyone an update.
 

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sorry to hear about that man. yeah I could see those problems with that. so much for the cheap fix. Well hopefully the truck does really well for you from now on.
 

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Discussion Starter #19
Picked up the truck and it is 100% better, just have an engine miss. The miss is only at idle and just off idle, once you get going and the rpm is above 100 the miss is gone. Can plug wires give off this problem? I would think it would be opposite nothing at idle and gets worse as the rpm and spark voltage goes up?

Any light on the subject?
 

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I'd pull the throttle body off and clean that, as well as some of the intake with some Berryman B-12. The spray seems to break stuff up better than Seafoam honestly, and is cheaper. I had a bunch of buildup on my tb. Sprayed it with the engine running at about 2500rpm's just to keep it from stalling out . Don't spray too much too fast or there is the chance you might hydro lock a cylinder.
 
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