Got My Car Tuned Yesterday And LOST Power
04-20-2017, 07:58 AM
#1
Staging Lane
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Got My Car Tuned Yesterday And LOST Power Well i recently did a 228r cam, 799 heads, BTR dual springs, LS7 lifters, TSP psuhrods, Yank 3k stall, and headers on my 1999 z28. I took it to the tuner and got a dyno tune yesterday and it put out 344.99 hp and 321 tq to the wheels. How???? IF anyone could help me figure out what is holding me back it would be very helpful. I think it is either my catback or my stock ls1 intake and throttle body. HELPPP.
04-20-2017, 08:19 AM
#4
Something is wrong with the engine itself, or the parts installed.
Verify spark, fuel and compression on each cylinder. Verify cam is installed correctly and pushrods are the proper length.
Once you get those results (and if they look good) then you can start looking at dyno or tune issues.
Verify spark, fuel and compression on each cylinder. Verify cam is installed correctly and pushrods are the proper length.
Once you get those results (and if they look good) then you can start looking at dyno or tune issues.
04-20-2017, 10:31 AM
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Im not sure if the converter was locked or not as i was not in the shop when he did it. I have just a flomaster 2.5" catback. If i didnt have spark or fuel, wouldnt it be throwing a misfire code now? My car did throw a Mass Air Flow code a couple hours after the tune. Also what is the best way to check psuhrods? Ill get the graph posted when i get home.
04-20-2017, 11:03 AM
#7
TECH Senior Member
That 2.5" Flowmaster cat-back is definitely holding it back. That, plus IF the converter was unlocked, would explain the power loss.
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04-20-2017, 11:06 AM
#8
Comp makes an adjustable pushrod length checker that is handy. Another method would be to check what your preload is with your current pushrods. With the cam on its base circle put the rocker to zero lash (resting on the valve and pushrod) then count how many turns it takes to torque the bolt to 22 ft lbs. Each turn equates to about .047" preload on the lifter.
04-20-2017, 06:59 PM
#14
Unlocked, the torque would likely be higher. So that sounds like it was a locked run.
And do you have baseline numbers to compare it to? If not, then how do you know you are down on power? Maybe your car baselined would have baselined at 250rwhp on that particular dyno?
The reason I say that is simple: don't go chasing a problem if one doesn't exist.
And do you have baseline numbers to compare it to? If not, then how do you know you are down on power? Maybe your car baselined would have baselined at 250rwhp on that particular dyno?
The reason I say that is simple: don't go chasing a problem if one doesn't exist.
04-22-2017, 04:40 PM
#16
Those jagged dips and bumps in the pulls are UGLY. Something is definitely going on. Was there knock on the pull? Have you done the compression test? What plugs and gap? It looks like it's having trouble controlling the motor or something is momentarily cutting out.
04-23-2017, 10:54 AM
#19
That could be A/F going lean or timing being pulled. Don't know just looking at the line. But the point is, that's before 5k rpm. After that, it seems to pull cleanly.
It could also be down a cylinder. That's about a 12.5% difference in power. Which would put the dyno around 390rwhp. Which is about right... And the misfire could maybe be seen at lower RPMs but as the engine moves faster and faster it smooths out?
It could also be down a cylinder. That's about a 12.5% difference in power. Which would put the dyno around 390rwhp. Which is about right... And the misfire could maybe be seen at lower RPMs but as the engine moves faster and faster it smooths out?
04-23-2017, 11:02 AM
#20
I don't think it pulled cleanly above 5k is my point. It's better, but there's still drops just not as jagged and pronounced and this is with smoothing set to 5. I would hope they could hear if it was down a cylinder, but you never know. I was wondering about knock and pulling timing myself.