Okay where do I begin? I've been having some issues lately with getting the car to atleast run somewhat better than halfass at idle and am failing miserably. Here's some background mod info to diagnose...

Crower 2's, exhaust cam at -2 degrees, intake at +4
head port by ERT, head was also shaved slightly for flatness
SAFC, stock injectors, walbro pump
new spark plugs, new o2 sensor
warm compression test reads 180 across the board.

First off you have to turn the key just right to get the car to start. By this I mean, turning the key and hearing the engine cranking (usually about 3-5 times) and once I hear it 'fire' I quickly release the key back to on and it will sorta sputter and then start up. By no means does it ever fire up strong like it should when you would crank her over. I think this might have some relation to the fuel pump right now...I currently have a switch controlling my stock FP relay to send signal to the pump to run at on. This was done due to an internal short (to the best of my knowledge) on the ECU of the FP relay signal wire (white/red stripe). I checked pressure at the rail while the pump is running and it checked out ok. I'm going to do Corbin's FP rewire this week and see what happens.

Yesterday I pulled out my IAC and cleaned it up. Upon reinstalling and starting the car back up, I can no longer get it to idle where it used to be at around 850-1000rpm. It now holds at 1200 and will drop to 1000 then back up and hold etc. Mind you the SAFC is reading anywhere from 180-260 mmhg while it is doing all this. I've been looking all over the engine bay checking vac lines, gaskets and am having a hard time trying to find any leaks. I've tried leaning it out at idle with the AFC and it's not helping any. EGT's are around 800 as well.

With the shootout less than a month away, this is the type of shit I don't want to have happening. So please, if anyone can help let me know. I've been using the search on this subject for a week now and have found some answers perhaps, but I wanted to post and see what others had to say with my description of symptoms.



http://www.dsmregistry.com/detail.php?carid=1185

Have you checked your coolant temp sensor lately?

Originally posted by .bs0d
Have you checked your coolant temp sensor lately?

As far as it being hooked up and connected yeah. Other than that no.


http://www.dsmregistry.com/detail.php?carid=1185

When my coolant temp sensor was bad the car would not want to start in the mornings and would even try to die a few times. The symptoms would clear up after the car warmed up, but If I started to drive it before the car completely warmed up, it would hesitate and cut out a few times.

Im just saying its worth checking out. Failing coolant temp sensor can cause a bad idle, and a new one is only $13 or so. Good luck

Originally posted by .bs0d
When my coolant temp sensor was bad the car would not want to start in the mornings and would even try to die a few times. The symptoms would clear up after the car warmed up, but If I started to drive it before the car completely warmed up, it would hesitate and cut out a few times. Im just saying its worth checking out. Failing coolant temp sensor can cause a bad idle, and a new one is only $13 or so. Good luck

It surely can eff things up all right. Your car may be warming up but the ecu thinks it's not up to temp yet so it dumps a bunch of fuel and will stumble.

Originally posted by Blizare
It surely can eff things up all right. Your car may be warming up but the ecu thinks it's not up to temp yet so it dumps a bunch of fuel and will stumble.

I started the car up about an hour ago on my lunchbreak and drove it back to work (runs perfectly normal besides the idle issue)...its idling better than it was last night, but now it threw a system to rich bank 1 code and my AFC is at -25% 1krpm lo thr and it stumbles slightly when I tap the throttle then revs up. So this could possibly be it by what you described.

However, the vacuum still seems rather low...it stayed around 200-260mmhg this time.

*Edit...I just remembered that while looking at my datalogger while the car was running, that the coolant temp was not off and looked like it had a normal reading? Could it still be a bad CTS?

http://www.dsmregistry.com/detail.php?carid=1185

At the cam settings you have, you added 6 degrees of overlap. This will take a little vacuum away at idle because of the scavenging.

Try setting your intake came back to 0 and see how it idles. You could even set both at 0 and should have a fair amount of vacuum, but just the intake cam at 0 should add a little itself. (-degrees on the eghaust side adds overlap, and +degrees on the intake adds overlap).

If you still have low vacuum after that, check anywhere you can for vacuum leaks, including the AIC, TB, etc.

My car also idled like shit when the o2 sensor went out, that's something else to check.

Originally posted by cougar694u
My car also idled like shit when the o2 sensor went out, that's something else to check.

I just replaced the o2 less than 2 months ago, and the car has hardly been driven maybe a 100 miles since that.

I'll try setting the intake cam back to 0 and see what happens.


http://www.dsmregistry.com/detail.php?carid=1185

I had a brand new one go out on me.

One way to test it unhook the o2 sensor completely so the 4 wires aren't hooked to anything. Secure the harness wires so they don't short. Use a volt meter to check the signal by hooking the black lead to the ground wire and the read lead to the signal wire. It should sweep properly, eventhough it's not hooked to anything. You should do this once the o2 sensor is heated up, or leave the heater wires hooked up (2 black ones).

bad idle, with it running fine off of idle, seems to be a cam timing issue. Did you compare timing marks from a stock gear, to your adjustables? I know sometimes the marks are not "perfect". I always make my own TDC marks on aftermarket gears, then time the engine with the gears at 0. Of course, if the timing was off when the belt was put on, then your gear settings will be off as well, but at least you can adjust them to get it closer to where it needs to be, without taking the belt off.

Originally posted by XtremeRS
bad idle, with it running fine off of idle, seems to be a cam timing issue. Did you compare timing marks from a stock gear, to your adjustables? I know sometimes the marks are not "perfect". I always make my own TDC marks on aftermarket gears, then time the engine with the gears at 0. Of course, if the timing was off when the belt was put on, then your gear settings will be off as well, but at least you can adjust them to get it closer to where it needs to be, without taking the belt off.

I've had this thought in the back of my head. When I had the gears set at 0 I checked for TDC (long screwdriver through spark plug well in cyl 1) and the marks line up. I always thought if the head was milled for flatness that your gears would be slightly off at TDC and that retarding this exhaust cam slightly would help get it closer to stock. They are Fidanza's, I can't think of anyone who has had an issue with these yet. However, I will take a stock cam gear and compare the two.

As for adjusting the gears to where it needs to be, should I just adjust the intake cam only? I've read on here before that most do not mess with the exhaust cam. I'm just trying to figure out which way would be the right way to advance/retard. I need to be sure of myself so I don't do it backwards. I did retard my intake cam back to 0 and the car seemed to be running slightly better, so I think it's safe to say I should retard it slightly more and see how it runs and so forth.


http://www.dsmregistry.com/detail.php?carid=1185

Originally posted by xcasbonx
I did retard my intake cam back to 0 and the car seemed to be running slightly better, so I think it's safe to say I should retard it slightly more and see how it runs and so forth.

Set the intake cam at -2 and see how it does. Typically, I wouldn't mess with the intake cam, but that's just my preference. Setting them to the same will provide the typical overlap of the cam profiles, and being slightly retarded can provide a little better top end.


**EDIT**
I dunno how often you go to the track, but have you ever noticed that those really high reving v8's take forever to start sometimes and they just crank and crank, then finally fire up and scream? That's from lots of cam overlap, it causes 2 main things, low vacuum (won't suck fuel out of carbs) and low cranking compression (harder to fire). Since you added 6 degrees of overlap, this is probably why you have trouble starting and low vacuum. My guess is that with both of them at -2, it'll increase your starting time and idle vacuum.

Originally posted by xcasbonx
Yesterday I pulled out my IAC and cleaned it up. Upon reinstalling and starting the car back up, I can no longer get it to idle where it used to be at around 850-1000rpm. It now holds at 1200 and will drop to 1000 then back up and hold etc.

Did you re-check the IAC seal ring? That thing is easily pinched during installation, possibly causing a vacuum leak.

Originally posted by fly1
Did you re-check the IAC seal ring? That thing is easily pinched during installation, possibly causing a vacuum leak.

Yes. It's not pinched. Oh I forgot to add that I found the slight vac leak...its off of my cruise control box. There are two small vac hoses, one is hooked up and the other is missing the the actual line, like it popped out, but the plug is still attached to the box. When I found it I covered it up while the engine was running, hardly made a difference if any.


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If there was any material taken off of the head, it will make your timing marks off slightly. I had .004" taken off, which made the marks off by 1/4 tooth or so. .008" was roughly half tooth. YOu need to take this into account with the adjustable cam gears. I've noticed that adjusting the exhaust cam makes quite a bit of difference over the intake cam, esp for idle quality. You exhaust cam is prob too advanced, so try retarding the exhaust cam and see how it idles. Remember, only half a cam gear tooth equals 5 cam degrees, and one full tooth is 10 cam degrees, so depending on how much material was taken off of your head, you may have to start with around 5 cam degrees..

Well good news.

I did the fuel pump rewire mod today and adjusted the cam gears. I set the intake cam to -2, and the exhaust cam at -4. I instantly noticed a difference from these settings. First, the car fired up right away and the fuel pump now has a strong current running to it which has helped some I believe as well as the cam gear settings. I'm getting around a 260-300 mmhg reading now from the AFC and idle around 850-1000...it's still bouncing a little off idle, but I believe with some more adjustments I can get it to idle a lil better.

Thanks for the help guys. I appreciate it.


http://www.dsmregistry.com/detail.php?carid=1185

the low vacuum thing is normal for those cams, like Luke said the overlap at those settings will cause the low vaccum.

also, when the IAC goes out, the computer still defaults and reads like 176* degrees if i remember right. causing a problem obviously like someone said during cold start and going away once warm. on the datalogger check it when the car is off and see if you think its accurate.