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Stalling issue after cam swap

greasegram

greasegram

Member Board
Joined
Dec 26, 2015
Location
kelowna, bc
Installed a new cam in my 93 240, now it stalls fairly often on deceleration (like when coming to a stoplight). The timing is correct, cam is timed straight up, vacuum lines are newish- I couldn't find any leaks. Other than this the car runs perfectly. Any ideas?

Thanks guys
 
I would double check that timing just to be sure. What cam? What did you set the valve lash to?

A mild cam LH will handle fine but something too radical might just make the fuel injection not know what to do without some programming changes.
 
what kind of compression ratio does the shortblock have?
That H-cam is designed to run with a high-ish CR.

if you have an adjustable cam wheel you could try advancing the cam timing a couple of degrees.

also: the idle circuitry should operate correctly. the mechanically adjusted base idle speed should be about 500rpm, the rest of the idle air should be provided by the idle control valve giving a total of about 800-900rpm. The engagement of the idle speed control is done by the throttle position sensor, with the engine off you should be able to hear that TPS click on/off when moving the throttle slightly off it's stop. If not it might need adjusting.
on top of this: in these older cars it is worth cleaning the throttle body and valve, over time they tend to gunk up. And this gunk messes up the idle airflow when the throttle valve is nearly closed.(= idle condition)
it's also worth it to clean the idle control valve (internally), carb cleaner works fine.
 
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I had some odd idle issues coming to a stop when I set the idle screw so it would barely run with the IAC blocked. When I set it by the book, the car wouldn't run without the IAC, but the idle was solid, and coming back down to idle performed much better.
 
My manual 93 with LH2.4 and enem V15 cam still idles fine at the stock 750rpm. 850-950rpm idle is for turbos. Cam is advanced 6 degrees. An H cam has more duration and overlap than what I am using and after making sure the idle system is clean and working. Advancing the cam timing is probably going to help a more aggressive cam like that.
 
Just took off for a week long vacation last night. When I return I will dig into the car. I plan on advancing the cam (have an adjustable gear). I timed it straight up just to see what it was like. I'll also clean the throttle body, I haven't done that to this car ever. It would idle fine around 800 rpm I'd guess, just every once in a while on decellaration it would stall when it should have idled. Thanks for the help, I'll report back later
 
greasegram said:
Installed a new cam in my 93 240, now it stalls fairly often on deceleration (like when coming to a stoplight). The timing is correct, cam is timed straight up, vacuum lines are newish- I couldn't find any leaks. Other than this the car runs perfectly. Any ideas?
Click to expand...

I would check the "top hat" on the turbo ... unless there isn't a turbo, which would be bad.
A split diaphragm in the re-circ valve would definitely cause your symptoms.

Three bolts, black rubber diaphragm.

"Diaphragm" is VERY hard to type by the way.
 
After getting back from vacation, my car won't run properly anymore. The idle is really low (400rpm or so), and its acting like it's misfiring. When I do a cylinder drop test the engine doesn't really respond to it. I can disconnect cylinder 1 and the engine barely reacts. It's the same across all the cylinders. It's also running stupid rich. I have rechecked timing, verified that I have spark on all cylinders, all injectors are firing. I replaced the plugs and the cap and rotor.

Does anyone have any idea what's going on?
 
I had a stock 1993 240 have idle issues after a VX cam install.

I would first do a battery disconnect and hope for the best.

You could also pop open the MAF and there should be a mixture adjustment.

Clean the t body and check for all air leaks. Reset the throttle body exactly per the manual.
 
I cleaned the MAF sensor and everything appears to be okay.. time will tell. I'm wondering if I had an air leak after the maf because the hose clamp was not overly tight.
 
Smoke test wouldn't hurt. At least pull the accordion hose and check for cracks and make sure it's mounted so it's not chafing anything.
 
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