Hybrid Idling Problems

[feavs]

Hey,

My hybrid is giving me trouble. When it idle's, it sounds like it has a huge cam in it, very lumpy and loud. I had my car sitting for over a month, while I fixed a power steering line, and it ran fine before it was sitting.

I have checked for vacuum leaks, and haven't found any. I've sprayed carb cleaner everywhere I could think of that would cause a vacuum leak. All the gauges are reading fine. I have swap IAC sensors, and that made no difference. I have checked fuel pressure, and it's fine. When idling, my car is holding around 15 inch/lbs (I think that?s the unit it measures in?) of vacuum. I thought it was suppose to be 20 or so? Don?t know for sure.

I do have cam in (GM 260 H with 1.6 roller rockers), but all of these components where in it before, and it didn't idle like this.

The engine has about 6500 or 7000 km on it since the full rebuild. I can't imagine a gasket is leaking. I bought new gaskets, including GM's new design of the upper/lower intake manifold. I did spray carb cleaner in that area, but I didn't see/hear it get sucked in.

Anyone have any suggestions?


For those who don't know what has been done to my engine, a list of things are at www.feavs.com

Thanks


feavs

https://www.feavs.com

[geoffinbc]

Check out the sensor perameters. The map sensor and ignition system come to my mind when you describe your problem. Double check that firing order

[feavs]

I hooked up the diacom scanner. All sensors seem to be checking out ok.

[rawag77]

Sounds like a vacuum to me... Does it only do this at idle, or do you notice anything while driving??? Might want to make sure all of your spark plugs/wires are connected well. I had a rear plug work it's way out on time and drove me crazy.

[geoffinbc]

What vacuum line do you have your EVAP canister hooked to?

[feavs]

My canister vacuum line is hooked up to my pcv line. It's always been like, and was working before. The reason I have it that was is because the stock vacuum line from the pcv also had a another hose attached to it with a 180 degree bend in it. I was able to find an adapter (lying in my garage) and just ran a new hose to the canister.

i took some sound files, but they didn't turn out worth a shit. I guess I'll try and redo them.



I also hooked up a timing light today, and everything seemed to be firing ok.

[geoffinbc]

No good. Old systems relied on a ported vacuum signal from the throttle body. Since 3X00 throttle bodies do not have a ported vacuum port you ahve to make one. Pull the line and plug it see if the condition improves. Raven had a similar problem.

[bszopi]

Speaking of Raven... Where in the hell has he been?!?

[RidgeRunner]

Offline... perhaps for a while.

[feavs]

No good. Old systems relied on a ported vacuum signal from the throttle body. Since 3X00 throttle bodies do not have a ported vacuum port you ahve to make one. Pull the line and plug it see if the condition improves. Raven had a similar problem.

I'm not sure if I get what your saying. But, I have already unpluged the line from the pcv, and plugged it with my finger while idling. Didn't make a difference unfortunatley. Is that what you meant?

I don't think I'll have to make a new line for the throttlebody, as the car ran fine before.

I should have mentioned before, that the line that hooks up to the pcv, also hooks in to the upper intake manifold, right behind the throttlebody. So they are sharing the same vacuum source, as well as the canister.


feavs

[geoffinbc]

Well the thig is that on the old cars the canister was closed until car car heated up. When it did it was switched open. Now the engine can pull vacuum on it and burn the fuel vapours. The thing is you do not want the car to pull vacuum form it while at idle because it will make it eratic because it is like a vacuum leak. So that it why the canister was on a ported vacuum line on the old system.

When the 3X00 came out the system went fulley electronic and the canister now controls its own release of the vapours and will shut off when certian demands call for it, like idle. So there was no problem with hooking it up to manifold vacuum since it could be turned off or on at any time and not allow a vacuum leak.

So since you have your canister hooked to manifold vacuum whenever the vacuum switch is open you have a vacuum leak.

Now I am not saying this is all of your problem but it could be part of it. Check out the TPS and ECT sensors aswell.

[feavs]

Hrm, I never knew any of that. I was under the impression the canister was just for warmup of the engine. Never put any thought into how it was opening/closing. Very good suggestion. I'll have to check into that.


Thank you,

[TRKK11]

Did you check to see if each individual cylinder has spark, compression, and fuel. The problem you described sounds more like a misfire than anything else. If it was vacuum, you would have a really high idle, and it would be rough, but it would not sound like it had a huge cam in it. My guess is that maybe an injector took a shit on ya. Do a balance test and determine which cylinder is giving you a misfire, if any, and then run the engine with a spark tester on that cylinder's wire, and while you are doing that, pull the plug and put your hand by the hole. If you have spark and your hand stays dry, then check the injector pulse with a noid lite, and if you have a pulse, check injector resistance.

[feavs]

Here are all the things I have checked:

Compression = 195 - 200 psi on all cylinders
Spark = I have spark at all plugs
Fuel Injectors = did a balance test (as mentioned above) and each were 6 psi right on the dot. Perfect
A/R ratio = According to diacom, it's running 14:1 to 14.7:1
Vacuum = I'm still only pulling 14-16 on the vacuum gauge. I have sprayed two cans of carb cleaner on everything that could affect vacuum, and still have not found the leak (if there is one)
Vacuum lines = I have checked each individual line, and they are all holding vacuum.


Things I've replaced or swapped out with known good:
- new Spark plug wires
- known good IAC
- new upper intake manifold gaskets (as I broke one)
- new throttlebody gasket (one that I made for my 62mm tb)
- known good coil pack and module
- known good MAP sensor
- known good ecm and prom


Does anyone have any other suggestions? Is the next step a engine tear down? I hope to hell it's not.

Thanks

[geoffinbc]

Check all your power and ground connections. Be sure you have the star washers installed so you get a good bite from one metal surface to the other. Also be sure the ground strap from the motor from the chassis is there. Check the terminals at the battery aswell.

Do not overlook electrical connections. I had a friend with an old caprice, he was hunting and idle problem for 2 years. My dad took a look at the car and pulled off a few connections and found corosion causing poor connections.