kane91z

ok before you guys go a head and say WTF!!! why would someone do that. The reason is my 305 chewed its cam - I need the car back fast for school and work so I took it into a 3 day engine shop. I told the guy I had an l98 cam but he said they couldn;t get any 305's with one. My car has been running like crap ever since I got this engine. So my question is could a peanut cam make an engine idle poorly and stall every so often -I know the spark curves are different for the auto and manuals and was thinking if that was because the manuals did have the l98 cam 90-92. Whenever I've posted here people always say its something simple like plugs, timing, wires, IAC... I've checked all of these things many times. I hooked it up to a scan tool and it is running rich and since the peanut doesn't move air worth $hit I thought that may be the culprit. Futher more the car makes about 40 hp less - oh well im getting a new cam this month anyways. Just wondered if anyone thought this may fix my prob. - thanks

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

ImportsRsloths

From what ive been reading, buy a good used LT1 cam!

MrJ

Ok heres the deal... or at least my theory

the peanut cam has a lobe separation of 109 degrees... the 90-92 L98 cam (which all LB9 cars are equipped with these years btw, auto or not) has around 115 degrees I believe. The low lobe separation, coupled with an ECM that is calibrated for a different cam profile, is causing the problem... also the MAP sensor isn't sensing as much vacuum as it should be... this is all conspiring to kill your idle. I don't see any easy way to fix this problem, you are just gonna have to wait and get a new cam.

Though its clear that you did what you had to do, personally I cant imagine taking my car to a shop as incompetent as the one you took yours to.

The reason for the difference between the auto and manual spark curves is because one car is an auto, the other a manual. Simple as that. If I'm not mistaken, manual cars get more spark advance sooner because they don't have a torque converter to multiply torque and get them off the line as fast as an auto.

Out of curiosity, what does the car drive like with the peanut cam? Is it dog slow now?

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91 Trans Am WS6
Bright White
5.0 TPI auto
Flowmaster 3" 2 chamber catback
Trans Go shiftkit
2000 stall converter
ported TPI setup

Built on Wednesday

kane91z

yeah with my exhaust and prom and such before it was faster than an auto lt1 - now Its slower than a v6 stang - actually this problem has made me learn so much about my car - but then I've replaced all the sensors - whole ignition system and exhaust along with tuning it as much as possible. The reason I though it might be the spark curve was cause it lugs at weird rpms like it doesn't at 1500 but does at 2000... but then maybe its the vaccum advance I dunno... the ecm really hates the cam too - if i reset it it will stall constantly for about 20 min till it learns how to deal with it slightly better...

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

kane91z

Imports: I'm gona go with the crane compucame 2032 - I really like the torque curve it has and I think it has the most lift I can use "safely" with the stock heads...

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

Kevin91Z

iTrader: (1)

My dad's converted RS still has the peanut cam, but he's using the good cam PROM. The MAP shows 30 KPa at idle and less when cruising. The stock TPI cam shows over 30, so the fuel and spark curve is definitely different. We've been able to tune it a bit so its more driveable. But it never stalled. Stalling means you have some other problem, usually a vacuum leak.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

kane91z

i've replaced all the vacuum lines and it didn't change a thing - the weird thing about all these problems is i've never thrown a code... there could be a leak in the intake - the only way i've heard to check that is to spray starter fuild around it and it the idle jumps then you have a leak but my idle is really crappy and junps constantly so i guess i can't check it that way... the car has oalmost 190,000 miles on it and the egr hasn't been replaced nor the injectors perfesionally cleaned - I was going to do both these things when I get the thing apart to do the cam swap... there used to be a page with step by step info on how to do it - but the link i had saved is now broken anyone have another??

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

kane91z

I've even taking the car into 2 seperate shops and neither could find anything causeing the problem - for about a year I was totally obsesed with the problem cause it was driving me nuts... I put my headers on when I did the engine and my car seems to stall mostly after its driven for over an hour straight - one of my theories is that the heat given off by the headers may be heating up my plug wires.. also that damn engine shop dented the crap out of one of my intake runners and latter after going over my car I found that the inside of one of my header primaries it dented - and they were brand new - the shop said they were already there - man those guys pissed me off so much... but all the other places around here wanted 2500 and they wanted 600 for the engine and 400 for labor so 1000 - I guess I got what I paid for ... ugh... oh and the day I got my car back - it wouldn't start so I took it back and they ended up (some how) charging me 350$ for a new tps - and I didn't even tell them to do "diagnostic work" I just took it back cause I felt they F_cked up. Man If i didn't need my car back right then I would have handeled it differently.

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

Kevin91Z

iTrader: (1)

I didnt realize you were in SoCal. Have you checked the EGR valve? If its stuck open it will cause stalling and hunting at idle. Have you reset the IAC and minimum idle? Sorry if you mentioned this already, I'm just throwing out ideas.

kane91z

the car won't idle under 1000 rpms - (thats how high I have to raise the min. air to get it to run) - we'll it will idle that low but not when setting the iac - i think the problem is just not enough vaccum cause it usually only stalls when i'm driving a while then throw in the clutch and stomp on the breaks - it seems if I pump the breaks it doesn't stall (as much) or if I break really gentley

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...

kane91z

and I haven't messed with the egr yet cause its such a bitch to get to - im gona replace it when I do the cam swap anyways - just in case...

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91 z28 lb9 5 speed - hooker 1 5/8 headers - high flow cat- full 3 inch exhaust - home made ram air - tpis airfoil - dual chamber flowmaster - Stage 2 Jet Chip and 160 stat - 8 mm Msd plug wires - 55,000 v hypertech coil/rotor/distrib. cap - Mac. White face gauges - lots of sound system crap...