Rough Idle/Stall Problem after Rebuild

[OneQuikSix]

I've been fixing fuel leaks, TPS issues, and other miscellaneous odds and ends since rebuilding this engine in the past few weeks. Here's my combo:

-109 block
-Full Throttle 210/215 roller cam with HS roller rockers (valvetrain sounds nice and quiet)
-Champion ported iron heads
-Champion ported factory intake
-237 fuel pressure regulator (no pressure gauge though)
-Tomco fuel injectors with green stripe (I think they're 32lbs but not sure)
-Unknown chip
-Unknown in-tank fuel pump
-3" dp-->dual 2.5" catback exhaust
-

Here's the deal. The car ran fine with whatever brand chip, fuel injectors, fuel pump, etc... prior to the engine swap. The only thing that has changed is the heads, cam, and intake. I've verified the TPS and cam sensors are set properly. The car will start without any problem, but it stalls within a couple of seconds. Also, after I get it warmed up by coaxing the throttle blade, the car idles very rough. Once idling, if I give it any gas, the rpm's increase, but the car dies as soon as I let off the throttle. At 2000rpm, the engine sounds very good. I cannot detect any vacuum leaks and the ECM is not showing any trouble codes. Also, I do not believe the car is running too rich at idle. If anything, I'm wondering if it isn't slightly lean. I can't stress enough how good I think this engine sounds (kind of a sinister sounding good ).

I've switched TPS and IAC with new ones with no change in performance. I realize switching the heads, intake, and valvetrain is a major change, but I guess I figured the car would at least idle and be somewhat drivable until I could add a proper fuel system to support my future goals.

Out of sheer curiosity, I unplugged the cam sensor while the engine was running and noticed no difference in idle or the engines propensity to stall after mild revving. I read on here somewhere some people advanced the cam sensor slightly to help with off-idle stumble and stalling associated with larger cams. I'm wondering if this is something I should pursue.

I'm sorry to report I do not have any scan tools at this point. If anyone has any suggestions, I'm all ears (errr...eyes in this case). Thanks as usual.

 

[WHEEZER]

How did you get the numbers set correctly on TPS,IAC and other settings without a scantool?

 

[1NastyT]

I am haveing pretty much the same issue as you and I haven't been able to come up with an answer either. Let me know what you find out. Good Luck!!

 

[OneQuikSix]

I used a voltmeter to set the cam sensor and TPS.

 

[84BuickGNYorkPA]

Well, there are a few things that you need for a engine that has volume now. Like a walbro fuel pump, hotwire kit, regulator and a gauge. Also some injectors that flow and a chip to match them. You need some way to monitor knock also ....... you don't want to hurt that new beast of a engine by being to lean. It sounds like your fuel pump is on it's way out, but with out a gage, it's a guess.

Chuck

 

[bmackinnon]

Huge combination change accompanied by:
Unknown chip? Unknown injectors? Non-adjustable 237 Regulator? No fuel pressure gage? No scan tool?

.... I'd start there, first.... just sayin'....

 

[OneQuikSix]

I hear you with the scan tool and fuel system. I've not had the car that long and that is at the top of my list of priorities after getting it running. I don't drive the car every day and am well aware of the damage knock can cause. I guess I'm just trying to make sure I don't have something else wrong with the car other than a lean condition (which I realize is difficult to detect without a scan tool). The fuel pump/chip and injectors in the car have been replaced with at least a stock equivalent or better. The car was running fine with the stock motor prior to the swap. I understand the car will need more fuel to support the greater volume of air it can now move. Shouldn't the car be able to idle with my current fuel system, or is my new combination so radically different from stock that the current chip cannot keep up? I'm planning on upgrading the entire fuel system and adding scan tools in the future. I was just hoping to 1. make sure I had all the bugs worked out from the swap, and 2. be able to start the car and move it around my garage until I can put together the cash for the new fuel system.

 

[bmackinnon]

Given that it ran fine before heads/cam/intake, you would think it should (?)at least idle, like you said.... however not having the scan tool makes it way more difficult to even begin to figure out what's wrong. Need to KNOW if it's rich/lean, temp sensors working, maf numbers look logical/reasonable, IAC, blm/int, etc, etc.... My FIRST guess, knowing everything's been apart, would be a major vacuum leak you just haven't realized.... are you SURE the cam sensor isn't 180* out? also NEED fuel pressure verification... basically, need more data.... :frown:

 

[OneQuikSix]

Success!!!...well, mostly.

After much reading and contemplation, I started thinking about all of the things I touched or changed in the process of the swap. I eliminated the TPS, cam sensor, maf sensor, O2 sensor, and other possible electrical causes I could think of that may create my car's symptoms (starting to sound like Gregory House MD. here). It then dawned on me that I should replace the crank sensor since my original was so dirty, I could have scratched the sensitive areas while cleaning with my non-sterile screwdriver. Turns out, the new crank sensor from my local Advance Auto Parts solved the problem. Car started instantly, and gradually idled down to normal rpms. Now I can happily begin the tuning process...and yes throw more money at this project my wife affectionately refers to as my other girlfriend.

Lessons learned:
1. Always diagnose and correct the underlying cause of the problem, not necessarily just the symptoms.
2. Consider causal relationships and understand that these cars do not break on their own. Usually, the operator has something to do with it. Work backwards and determine when the car last ran properly and recall what changes (stimuli) were introduced to effect a change.
3. Only change one variable at a time if at all possible.
4. When truly confounded and seeking input from others, graciously accept their input as many fellow board members here will probably forget more about these cars than you will ever learn.
5. Lastly, give thanks to all who took time from their busy lives to contribute towards your solution. Also, update your pleas for help with the outcome so others (like myself) can search the archives when dealing with similar problems.

THANKS TO EVERYONE

 

[1quick6]

Your lessons learned are very well put. However, I will contend that these cars DO break on their own.

 

[OneQuikSix]

UPDATE...More Success

Just to give you folks an update of my rough idle issues...

In the last two weeks, I tested for vacuum leaks by using my air compressor and a spare silicone intercooler hose attached to the throttle body. This involved replacing the factory plastic vacuum block with an aluminum one that could be adequately tightened without causing leaks. Additionally, I replaced all vacuum lines and zip-tied everything where I could. Now I am confident that everything will stay put when I get into the boost later on. This was well worth the time and inexpensive homemade tools I used to check for leaks. I was blown away with how many vacuum lines appeared to be sound but leaked SEVERELY under even minor boost pressures. FYI...some people have used hobby smoke to more easily visually identify the source of even minor leaks.

Also, I replaced the PCV valve with a new Delco one from Kirbans. I installed two really nice valve cover breathers in my Champion "Buick 6" valve covers which are extremely well-built BTW. The result is no more oil spewing out of my dipstick onto the exhaust manifold. This is a good thing!

Tonight, I swapped fuel injectors and chip (which turned out to be green stripes and a stock Delco chip) with my new 60lb Motrons and a TT chip from Eric Marshall. Let me say WOW. I know everyone had positive things to say about his chips, but, WOW. Night and day difference. Also, I discovered that the stock fuel injectors and chip will not support a combination radically different than the stock engine (ie ported heads, intake, 210/215 roller cam). The car would not even idle properly. I would constantly have to keep my foot on the gas pedal at stop signs and would have to gradually lift from the accelerator or else the car would stall. Now, with no other changes, the car idles and drives great. I made a point to mention this because it may save someone else time in trying to diagnose a similar issue.

My next issue will be to replace what appears to be a faulty TCC solenoid. After that, I don't think I would hesitate driving this car anywhere. Hopefully, I can spring for some tuning equipment and a fuel pump/hotwire kit. Believe me when I tell you it is tough for me to keep my foot out of the boost. However, I won't even consider it without a proper tune and monitoring equipment. I've been down that road about ten years ago with my old TType and have no desire to return. I'll keep you all posted with updates. Thanks again for all of your suggestions.

 

[84BuickGNYorkPA]

Great! Glad to here you are on the right track now.

Chuck