LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

confused and needs help?

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Old Jul 22, 2003 | 02:52 PM
  #1  
chevy1963's Avatar
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confused and needs help?

Ok here's my problem, I hope ALL the experts can help, or get me in the right direction.

Check the mods below. Well I had the car dynoed a few weeks ago and it got 207 HP with the below mods. The guys dynoing the car said the air/fuel ratio was 17.1 So noticed that I have the LT's with emmison hook ups and I had the wrong O2's in. I didn't have the HOT o2's in so i made the switch and installed a air/fuel ratio gauge and it seems to be working fine, but do i have to buy O2s sims for the second set of 02's that i left disconnected under the car. would this cause a MAJOR pwoer loss?

well i them went to the track this weekend and with the samw set up I could only run at best 14.6 when before I ran a 13.9

I think this car should be running faster then 13.9 with these mods.

Can any hel p with this... IT's starting to off. and before I spend more money I 'd like to get your input

THanks
Old Jul 22, 2003 | 02:56 PM
  #2  
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My guess is with traction you should be mid 13's at a decent sea level track. However 207hp isn't going to get you there. Something is seriously wrong. I'm actually suprised tou ran in the 14's with only 207 hp. Perhaps the tranny/torque converter is slipping and you did not get an accurate dyno graph? Can you post the chart?
Old Jul 22, 2003 | 03:01 PM
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The car is all so back firing sometimes when I get off the gas. I ran a 14.6 this past friday after the dyno and I'm having 2.1 60 foot times.

I'm replacing the plugs today. AC delcos

I also don't have the air pump hooked up to the headers it just blows air out of the tubes will this cause power loss?
Old Jul 23, 2003 | 10:38 AM
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TTT, does any one else have any in put? shoebox maybe?
Old Jul 23, 2003 | 11:29 AM
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Originally posted by chevy1963
The car is all so back firing sometimes when I get off the gas. I ran a 14.6 this past friday after the dyno and I'm having 2.1 60 foot times.

I'm replacing the plugs today. AC delcos

I also don't have the air pump hooked up to the headers it just blows air out of the tubes will this cause power loss?
it's not going to help anything... and it's going to MAJORLY screw up your O2 readings... you get them plugged and then see what happens...

basically you have a HUGE header leak if you have the AIR fittings open...
Old Jul 23, 2003 | 11:34 AM
  #6  
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You really need to ask for help BEFORE you do the mods.... wrong O2 sensors, no O2 sims in the aftercat position, open leaks from the missing AIR tubes..... I'm surpised it ran 14.6

Do you have an SES light? Have you had it scanned?
Old Jul 23, 2003 | 11:47 AM
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sorry, I forgot I did block off the hole on the headers where the AIR pump tubing hooks into, The AIR pump is just throwing hot air out the brass tubing because i don't have them blocked.


I do have the right O2's in now. I don't have the secondary O2's hooked up.

My car had dual cats so 4 o2 senors 2 before the cat and 2 after. I don't have the 2 after hooked up.

The car isn't thowing any codes either.
Old Jul 23, 2003 | 12:24 PM
  #8  
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Originally posted by chevy1963
..... The AIR pump is just throwing hot air out the brass tubing because i don't have them blocked.....

Maybe a few of us misunderstood your original comment... I thought you meant the header AIR connections were open... and I think 97FormulaWS-6 had the same conclusion. Just dumping the AIR pump output (if that is what you are saying - still sort of confusing) wouldn't hurt anything, as long as there are no holes in the headers.
Old Jul 23, 2003 | 12:27 PM
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yep, I may have worded it wrong. no holes in the exhaust no leaks.

any suggestions on why the times are bad.
Old Jul 23, 2003 | 12:34 PM
  #10  
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What was the MPH on your 14.6-second pass? MPH is a much better indicator of HP than the ET. What was the temperature and barometric pressure (or equivalent density altitude) when you ran?
Old Jul 23, 2003 | 01:19 PM
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the MPH was around 94 I'm not sure what the bar pressue was but the humidity was about 50% and the temp was 80.

I ran a 13.9 at 100 with the same set up but that was with the wrong O2's in.
Old Jul 23, 2003 | 01:23 PM
  #12  
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94MPH would indicate even less HP than you dyno'd.... about 235flywheel/192rwHP. The high temp and humidity might explain the further loss below 207rwHP.

Definitely major problems on the engine, and not surprising at 17:1 A/F ratio (assuming they put the sensor in the right place????). You need to find out why its not getting enough fuel, before you grenade the entire engine.
Old Jul 23, 2003 | 01:27 PM
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I did hook up an Air/Fuel ratio gauge since the dyno and it's reading Stoich, not even close to lean more on the rich side.
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