410 and/or 422 Cam idle behavior

[WilliamWallaceGS]

Hello all,

Hopefully some of you guys with experience with either of these cams will chime in, I did a search for this, but did not find my answer. How much does adding either a Comp Cams 410 or 422 grind cam on our 4.0s impact the idle behavior? The reason I ask is because I recently installed a 410 in mine, and after a few fiascos (I need to update my other thread with what I've done since) am just now able to drive the truck for an extended period of time, and my idle seems a bit goofy. I did the idle reset procedure, and she'll hover between 8-900 rpm when warmed up, she doesn't like much below that. Occasionally it will stumble under 800, and it will bog a little bit, but usually bounces right back. The idle is not as smooth as it was prior to the cam install, but I'm attributing that to the cam.

I've checked all of the normal things, fuel pressure, coil resistance test checked out OK (and I cleaned the coil ground plate/mounting bracket/other ground connections), new wires/plugs, IAC valve and TPS are new (TPS voltage is within spec), coolant temp. sensor and air temp sensor check out OK, MAF was cleaned, no codes. I've sprayed carb cleaner around checking for vacuum leaks and didn't find any. Any other time driving is butter, but just the funny idle.

This is the first vehicle I've owned with any sort of aftermarket cam, and I'm just wondering if this is just the nature of the beast, or if I have some other issues. I figured with the mild 410 that an idle change wouldn't be noticeable (so says Comp Cams), which is why I went 410 vs 422 since this is my DD. Thanks for any insights.

 

[WilliamWallaceGS]

I forgot to mention I've got an automatic trans, I know the idle characteristics with those are a little bit more finicky than with a manual with a cam installed.

 

[Ronin8002]

Look for posts by, or send a PM to JD4242. He's running the 422 now and I believe he also ran the 410 for a bit....definitely the guy to go to.

 

[jd4242]

Both cams I've found the idle needs to be turned up with an auto.the 410 is not as bad for sure but mine had to be around 800 also.the 422 has a much more pronounced lope to it and needs a hair more rpms.idle in park doesnt seem to be the problem but when in gear it needs more rpm as a auto drops you a bit and I think the a4 being vacuum controlled effects it also.if it gets tuned you can fine adjust the idle but most just turn it up alittle, just make sure you dont turn it up out of the range of the iac and check for vac leaks EVERY WHERE.

 

[jd4242]

Also the 410 &422 cams are very similar. The 422 just produces way more power mid and up top.also has more overlap.any cam in a motor is going to give alittle lope and idle will be affected to a degree.camed motors aren't made to be idling or going slow.

 

[WilliamWallaceGS]

Thanks for the replies guys.

The lope from a 410 wouldn't cause the whole truck to vibrate though would it? That's where I am, the thing shakes/shutters and hovers between the rpm range, almost like it wants to stall sometimes.

From the feel of it, I definitely think something is amiss. I did another vacuum leak check with carb cleaner last night after I got home and got nothing. The only thing I haven't checked is the rubber line on the trans modulator, could have gotten old/worn down there. I'm going to take all of my vacuum lines off from the tree/TB and plug them (except for FPR) and let it idle to see if it helps any. It is much more pronounced in gear, coasting down my road it will hang around 700 rpm and act like it's struggling, same thing on initial input to drive or reverse. The slightest bit of throttle brings it back up and it's butter until I let off the gas. It sounds like a small vacuum leak, (and is worse when it's warmed up or warmer outside) especially since driving at speeds above idle the thing runs great.

 

[jd4242]

Where in Hampton roads are you? If you wanted I could take a look at it.im in the kempsville area but work in Norfolk.

 

[QueenCitySleeper]

I had HUGE idle problems after my cam(422) install. High idle, hanging rpm, stalling, rough idle you name it. Two nights ago I replaced some valve cover gaskets and found a vac hose unplugged burried deep under the upper intake. It was a red vac line. Take your time and follow every vac line end to end off your upper intake. Mine now runs smooth as glass. JD ain't jokin when he says check ALL vac lines. Also check the soft rubber boots at the vac line ends, they could be dried out and cracking. If you can't find any leaks by eye there are other ways(ether:shifty_ey)

 

[malohnes]

The rubber boots on some of the vacuum lines can dry out and crack. I used silicon wrap that sticks and seals to itself with 100% success so far. The trickiest one I found was the one to the FPR, followed by the connection to the brake booster.

Your problem does sound like vacuum, but I can't help but think that you have plug wires crossed up.

Seeing how I am going down this road once I get my drive train upgrades done this summer, I am following your progress.

 

[WilliamWallaceGS]

I appreciate the offer JD. I'm in the boondocks of Isle of Wight County, so I'll let you know if I'm about to pull my hair out and need some assistance. I still want to try a few things first.

When leaving work today, fired it up and put it in gear (It was 70 some degrees today FYI). When I went to hit the gas initially, she just bogged down. Gave it more gas and no change. Then after a few seconds, she picked back up. I got it home and sprayed carb cleaner EVERYWHERE. I doused every single vacuum line/intake hose that was in the engine bay and got no change, making sure I sprayed the boots and all (thanks for the tip, malohnes). Sprayed it all over the intake, TB, IAC, temp sensor, vacuum tree, and nothing. I unplugged the Trans. Modulator line and stuck my finger over the hole and let it sit for a second and nothing changed.

Like I said, when it's freezing out, it idles pretty good until the engine warms up. I'm not completely sure it's NOT a vacuum issue, but since temp. seems to play a factor here, I'm wondering if my coil, ICM or other electrical gremlin is the culprit...but then why only at idle? For a vehicle 19 years old, stuff starts to wear out. This thing is starting to irritate me now. Anytime I came to a stop today, it would sit there and shake around 7-800 RPM, today was one of the worse days I've had with this thing.

 

[jd4242]

Re tighten your lower intake.then i would start unplugging stuff like the maf, tps or iac and see how it runs.have you done a vacuum test on it?

 

[WilliamWallaceGS]

I did a vacuum test initially once I got it all back together, but it was cold out and the idle wasn't all that bad (I thought at that time it was just the cam). IIRC, I was getting around 17 in HG vacuum, and it varied about .5-1 in HG in either direction (is that normal/good for a cammed 4.0?). I'll test that today when I get home and it's nice and hot and see what I get.

I'll check the lower intake manifold bolts too, just in case.

Then I'll unplug stuff. I know for sure unplugging the IAC makes the RPMs drop and the engine bogs, and I've tried that on two different IAC valves and same thing, so that seems to be working properly.

 

[jd4242]

Do a test when it is acting up.but 17 is fine, I ran about 16-18.doesnt sound like a vac problem

 

[malohnes]

Just for reference, with fresh 95tm heads, valves, seals guides etc, AND not having a 410 or 422 cam, I pull 20-22 inches at idle. On deceleration I can almost pull 28 inches. You should see less, but how much less is one question I don't have an answer to.

I agree at looking at your U&LIM studs/bolts again.

 

[jd4242]

Just for reference, with fresh 95tm heads, valves, seals guides etc, AND not having a 410 or 422 cam, I pull 20-22 inches at idle. On deceleration I can almost pull 28 inches. You should see less, but how much less is one question I don't have an answer to.

I agree at looking at your U&LIM studs/bolts again.

Being he has the 410 he should probably see closer to 20ish.seems like when I had the 410 I had more vac.I should clarify my last post.I see 17-18 with the 422 and sc.I said he should be fine with 17 based on the cam and usually when you have a vac leak that is causing stalling or problems, you see much less vac than 17

Side question.hows your motor running?

 

[malohnes]

jd - thanks for asking. Running fine, but still have a couple minor issues that stem from, I think, LIM bolts not wanting to stay torqued down and leaking oil down the back side of the engine.

With your boosted engine, how are you measuring vacuum? I have a boost/vacuum gauge, and w/o a blower, I only deal with vacuum.

 

[jd4242]

jd - thanks for asking. Running fine, but still have a couple minor issues that stem from, I think, LIM bolts not wanting to stay torqued down and leaking oil down the back side of the engine.

With your boosted engine, how are you measuring vacuum? I have a boost/vacuum gauge, and w/o a blower, I only deal with vacuum.

I have a boost vac gauge in the dashI have 9 total just one side

 

[WilliamWallaceGS]

Just got in from some troubleshooting. Don't want to prematurely shout "Eureka", but I think I found the culprit.

Took some Fuel Pressure measurements.
KOEO: 36 psi
Running: 30 psi
Running w/o vacuum line hooked to FPR: 38 psi.

OK, now the vacuum readings.
Slightly shaky idle (the new "norm"): 17-18 in. HG.
Crappy idle: 15-16 in. HG.
in reverse (wheels chocked): 12-13 in. HG. <----yikes

So I started unplugging things like MAF and TPS. The engine responded accordingly and got worse. So I decided to look at my coil (and checked my wire routing for the 8th time...it's right).

Unplugging wires for 3-6 on the coil the engine bogged and vacuum dropped. Unplugging 1 and 2 and virtually no change in vacuum. Hmmm, so I swapped wires around to see if they were the culprit. Same things, 1 and 2 on coil didn't do jack, 3-6 responded accordingly. Then I decided to swap some plugs around. Same thing, 1 and 2 coil didn't do jack, 3-6 responded accordingly. There was arcing between the wire and coil on all 6 as I pulled them off (even felt a few, woops), but I couldn't tell if the spark looked "weaker" on 1 and 2, but unplugging them spoke volumes. Plugs looked OK, gaps were OK, smelled a little off though, kinda burnt smelling.

Looks like a new coil it is. I will probably go with OEM Motorcraft vs. store brand just because I know mine lasted this long and rockauto has them, and I can drive one of my other vehicles in the down time. I'll keep everyone posted.

 

[WilliamWallaceGS]

Oh, and I checked my lower intake manifold bolts before the coil deal. Those were still nice and tight.

 

[jd4242]

Hell yea.hopefully thats it.keep us posted