kuntz98

I have a 2002 LS1 in my 04 RX-8 that I have installed and wired in. Upon start up it has a weird miss and I'm hoping someone can give me a heads up on here.

The engine has upgrades as follows:
Stock bottom end with ARP Hardware
PRC Stage 2.5 Heads 58cc
Stock pistons were flycut to clearance at .9 int. and 1.15 exh.
248int 254exh .625 .620 cam
Comp Cams 7.4 Pushrods .080 thick chromoly
P&P stock TB
Ported LS6 Intake
Green Giant Injectors
SLP 85MM MAF
Texas Speed Mail in Tune
All new Sensors (Cam, Crank, Map, MAf)

That about sums all the upgrades up. Now here's the issue. It has a weird stumble any time I hit the gas. It almost shuts down... I have put a new CKPS, CMP, and Map Sensor in with no change in how it runs. I hooked up a tech 2 to it and it isn't showing any misfires at all. I suspected the injectors so I went through and shut them off and then back on 1 at a time and you can tell the difference with every one, the odd thing is when I shut down the 7th cylinder injector it pretty much makes the engine completely shut off. I checked the reluctor wheel for any bent or broken teeth on it when I replaced the CKPS and it is nice and straight. I put new intake gaskets in and no change. The spark plugs are new via engine build and it has only run for about 30 minutes total so I wouldn't think they are fouled but I'm going to replace them with TK55's @.050 gap tonight. Any help would be greatly appreciated. Thanks in advance.

Kuntz

LilJayV10

iTrader: (39)

Have you done a compression check? Also did you do a relearn after the new crank sensor? I have nothing on why #7 killed the engine though.

kuntz98

done a relearn on the new crank sensor, compression check is in progress right now.

3rdCoastPowerSports

iTrader: (5)

what were the results???

joecar

Check crankshaft thrust/endplay.

LilJayV10

iTrader: (39)

X2 on the results. Also, where you able to look at the wave signal from the CKP? The reason I ask is if it is that sensor, you "should" be able to see it mess up on the graph when the idle goes to ****.

Burken01

iTrader: (88)

Try a dyno tune at a local tuner, that's a huge cam... I wouldnt trust a mail tune on that.. JMHO though..

kuntz98

I found 2 bad injectors so now I'm waiting to save some money for a set of green tops. Didn't get through the compression check, had to start working on the "honey do" list that I've been neglecting. I should be getting some time this saturday so I will have some results to post then. Thanks for the advice all. I'll let you know how it goes.

Attached is a picture of the ls in my RX8.

kuntz98

compression test came back perfect, everything was around 160ish. Waiting on some money for the injectors but I'm hoping that they will resolve much of my issue. THanks for all the help everyone.

Cooldude5231

iTrader: (6)

even if the injectors fix the problem, id take the car somewhere to be tuned.
has stated above thats a pretty big cam,
i wouldnt rely on a mail in tune for something that big
thats just my $0.02...

Russ K

iTrader: (1)

If you have any Maf codes, the misfire counts will stay at zero.

Russ Kemp

v8 that rex

kunts i saw on the rx8club that you weren't interested in cluster gauges, but i am. you mind if i throw some questions your way to see what your opinion is? any anyone else of course.

What would be the easiest way to have the ls1 computer control the fuel pump while having the rx8 computer read the fuel level?

For the tachometer how would one mount the eccentric shaft position sensor (this is how the rx8 gets the rpm's) onto the crankshaft? does the ls have a crankshaft sensor? could the rx8 wires be spliced into the ls crankshaft sensor and have the same readout as the eccentric one while the LS gets it's own rpm input?

For the oil level sender how can the rx8 oil level sender which is in the oil pan be placed inside? drill through and weld shut around a rubber filled rod?

For the rx8 vehicle speed is needed for the cruise control if the ls1 computer doesn't get the vehicle speed input from the ABS system how would it go about controlling this? would it be wise to splice into those wires from the ABS and feed them into the ls1 pcm input for speed? or better to attach another vss to the front right caliper. (ABS vss for the rx8 is on the left)

should the rx8 air compressor be used for A/C and fab a mount for it?

would you trust the rx8 coolant temperature sensor to handle the cooling fans and the ls1 water pump to move the water? fortunately ls1 runs colder than the renesis.

should a t-splitter be used for both the ls1 and rx8 oil pressure sender to read to both pcms? Same with the coolant temperature sensor?

If splicing will produce the same voltage and ohms going to both computers then it would be very easy to go this route, but i'm no electrician.

Would 2 injectors really take your idle to it's death bed? Does this happen mostly under load? any a/f ratios?

ZDER

iTrader: (3)

Do a compression check, #7 is usually a hot cylinder in ls1s ... change injectors and see if coils are all working and plugged in.. sometimes coils will do stupid things like that. Good luck and that's a siiiick conversion! Does it still handle as good now with the ls1 in it or did it change it drastically? Bet it would destroy a **** ton of cars!

chrisfrost

iTrader: (8)

Do a search on here for vss ,,,,,there is info about a speedo cable from a caprice that has a vss in the middle and has the correct x's