Hello, i recently changed my setup with :

* LE2 heads
* LE1.5 cam
* Holley 52 TB
* SVO 30
* new O2 sensors
* a new tune for all with Ion

i have now the problem : when i start the car the idle is not really good and sometimes erratic. it uses to be at 1000 RPM but fall to 600 as soon as you engage transmission. When idle fall, i have also a DTC code 33 but it goes when you drive and RPM get higher. the pressure manifold might fall also with the code because you lose break efficacity.

HAve you any suggestion on what to check to solve this problem ? Before making these changes, the car was running really fine.

Pierre

 

Sounds like vacuum leak. It could be a bad MAP but its more than likely a hose is off or the manifold is causing it. My break booster hose was not on all the way and caused problems when i put the brake on.

 

What are the programmed idle speeds, in neutral and in gear? Did you set the throttle stop screw, while checking for the correct idle speed, IAC motor position and TPS voltage? How does the IAC motor "counts" respond when the idle speed drops?

Low vacuum/high MAP can be caused by cam overlap, incorrectly adjusted valves, misfires, and vacuum leaks. You have to rule these out one step at a time. As far as the brakes, its the other way around... the low vacuum (high MAP) causes low power brake booster performance. Using the brakes doesn't cause low vacuum/high MAP. Not sure what you mean by "efficacity".

 

Thanks for your help. I check what Ion sent me. The idle should be at 875 in gear and eutral (same).

I havent touch the throttle stop screw but even if i try to open the blades, the idle is rough.

For the TPS, i slot the holes in it to adjust it to not get a code. I had one before and the voltage was bad. I don't remember where i put it but i have no more code about TPS.

I haven't checked anything on the IAC. I will look and tell you.

about valves, i double checked the adjustment.

having search for a possible vacuum leack and haven't found any but wondering if i put all the vacuum lines at right place ??

also : is there a way to check the opti ? mine is new but I have drop a little water on it at some times during the assembly. I wonder also, why water can cause an opti to have problem ?

sorry many questions.

I will check IAC counts and let you know

Pierre

 

Water can cause the Opti to have problems because a component that is switching 30,000 volts from the coil to various spark plugs does not like water. Water causes the spark to jump all over the inside of the cap, instead of flowing from the tip of the rotor to the individual button on the cap. In that respect, it is no different than any other distributor.

Water also causes the components inside the Opti to rust, and the rust particles blind the tiny slots in the rotating disc, and clog up the two tiny LED emitters that shine through the slots, and the receptors that detect the light.

You have to do things in the correct sequence. First you adjust the throttle stop screw very slowly, until the engine is idling at the prgrammed RPM, and allow time for the IAC counts to stabilize. They should be in the range of 20-40 counts, but a little higher is OK with a cam. Only then do you measure the TPS voltage to make sure it is in the correct range. If you got a code for high TPS voltage, and immediately slotted the TPS and started rotating it, without checking the throttle stop screw, you did it incorrectly.

You might also want to check with Bret to see if he feels the LE1.5 cam has enough overlap to cause the low vacuum/high MAP code to set? This isn't the first time I've seem someone with the various LE cams getting the DTC 33 code. Not to say its anything wrong with the cam... its not. But if there is enough overlap to significantly reduce vacuum at idle, it increases the chance that minor issues with misfires, valve adjustment or vacuum leaks can be enough to push it past the limit and set the code. Since you appear to think you are having problems with the Opti, is this because of a rough idle or misfires? As noted, misfire will destroy vacuum.

 

hum i finally took time for my problem.

My IAC stays over 86 all the time whatever the adjustment i can make to to blades position. It even goes higher when i close the blades ?

Is there a way to check the IAC ?

 

[QUOTE=Injuneer;4858533]
You might also want to check with Bret to see if he feels the LE1.5 cam has enough overlap to cause the low vacuum/high MAP code to set? This isn't the first time I've seem someone with the various LE cams getting the DTC 33 code. Not to say its anything wrong with the cam... its not. But if there is enough overlap to significantly reduce vacuum at idle, it increases the chance that minor issues with misfires, valve adjustment or vacuum leaks can be enough to push it past the limit and set the code. QUOTE]

We are having these probs with our car as well. Rough erratic idle, DTC Code 33 is the only code thus far. Opened up the blades a bit the get the IAC counts down, was into the 140's at times. Not sure what the idle was programed, will check on that. We have a couple of issues with an arcing plug wire (brand new too), and loose linkage on the TB, replacing both. Hopefully this will help. All the while the car is running rich as heck. Not eye watering, but still a bit on the overpowering side. Interesting what Injuneer said about the cams. It's a 290/307 Comp Cam. Is that enough with the other trouble to set the DTC 33 ? Wondering if this is what is going on with ours.

 

what was the problem in the end or not figured out yet?

 

i will look during this Week end. I was away a few days because of work. I'm not beleiving it might be some IAC issue. Any advice on what to check on it would be welcome.