Tune changes with open headers?
Tune changes with open headers? Probably a dumb question but Ive been wondering. I have a cammed 02 ls1 and got some new headers ( i had 1 3/4 hookers, went to 1 7/8 tsp) and with the way the new headers sit under the car my custom duals wouldnt fit with the stock tq arm the way it did before, anyway I left the shop and am currently running open headers (till i get my mwc 9"/new tq arm).
I realize this isnt ideal as it was tuned for the duals and what not, but am I going to hurt anything being that there is a substancial loss of back pressure compared to before? It runs a bit rough (misses sometimes, had ses flash once while driving) until about 2500-3000rpm and then seems normal again just WAY louder. I dont have a wideband, so I dont know what the afrs look like in its current condition. As a rule of thumb would it lean or richen with the changes I made?
Im not driving the car till I can get the new rear in and get the duals redone. The shop mentioned that during the header swap one of the plugs was cracked so they replaced that one and re gapped it to match the one they took out, could there possibly be more cracked plugs causing this rough running?
Thanks for any help you can provide
Eric
I realize this isnt ideal as it was tuned for the duals and what not, but am I going to hurt anything being that there is a substancial loss of back pressure compared to before? It runs a bit rough (misses sometimes, had ses flash once while driving) until about 2500-3000rpm and then seems normal again just WAY louder. I dont have a wideband, so I dont know what the afrs look like in its current condition. As a rule of thumb would it lean or richen with the changes I made?
Im not driving the car till I can get the new rear in and get the duals redone. The shop mentioned that during the header swap one of the plugs was cracked so they replaced that one and re gapped it to match the one they took out, could there possibly be more cracked plugs causing this rough running?
Thanks for any help you can provide
Eric
More than likely, the headers are just throwing codes. They can throw a bunch. They will mess with the 02 sensors as well. If you had a wideband it would probably not read right either with no exhaust.
Ive currently got 02 sims in the headers, so it isnt throwing any codes related to that. From some of the reading Ive done it looks like it should be safe to drive though?
If it still miss, yeah most definitely there might be more fouled or cracked plugs. Check them all to be sure.
If you got simms in the front 02 plugs and the tune still usses the 02's it is not running right and can do damage long term.
FWIW when it was tuned the O2 sims were in there, it just had the full exhaust on it. All that was done was a header swap, and the duals were not re installed if that helps clarify better. Thanks again for all the info guys.
Eric
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Now I'm really confused, where are the downstream 02's located then? Since I've had the car it's had LT headers and had the sims when I bought it. If it was tuned with the 02 sensor arrangement as is, with the exhaust being removed will I risk damage?
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Verdad Gallardo Down stream o2s are for after the cats. They were probably taken out when the headers were originally done. Most people ditch them.
As for sims...im not a tuner so idk but it sounds like slowhawk answered your question.
As for sims...im not a tuner so idk but it sounds like slowhawk answered your question.
If the headers are wide open with the 02s at the end of the collector reversion
will drive them apeshit. A couple feet of pipe would make a big differnce. It will run better
with them unplugged. You need to get the exhaust back on the car.
will drive them apeshit. A couple feet of pipe would make a big differnce. It will run better
with them unplugged. You need to get the exhaust back on the car.
Ok, I was under the impression that the sensors at the collectors were the sims but they are the actual front 02s. Makes sense now.
So having driven maybe 10-15 miles with a lack of exhaust are my 02 sensors going to go bad? In retrospect I should have had my exhaust shop throw some bullets and turndowns on till I can get the duals back on.
So having driven maybe 10-15 miles with a lack of exhaust are my 02 sensors going to go bad? In retrospect I should have had my exhaust shop throw some bullets and turndowns on till I can get the duals back on.
