New 3.2-rough idle and part throttle, after that smooth and strong?
 

I got my newly rebuilt 3.2 in. Ruby is alive again, with an asterisk.....

She runs, but idles rough and runs rough on part throttle, but anything over about 1/4 with a load it smooths out and pulls nicely to 5K. I'm kind of scratching my head, but here is the back story:

1. I had my injectors cleaned and flowed back in July. I didn't realize this is a no-no. When they sit, they stick. I took a 9V battery to energize them while installed, and got clicking. After doing this, I got the engine to at least fire, and run as it is. Truthfully, I still think they are a problem, as it only is an issue until the engine gets a load and some throttle. I talked to WitchHunter, and he said it is probably best to send them back in....

2. My crank sensors are new, but I am going to recheck the gap-I took one of the old ones, and epoxied a .8mm shim on the end to check the gap.

3. The CHT had been replaced, it is the 2 wire version. But, it isn't new, and I suppose if it was old enough, something could've gave way with the handling during my rebuild. I tried unplugging it, and the engine went crazy, so that may tell me it is working?

4. I've got low temps on the headers where the exit the heads on 3 cylinders: 1,2 and 5. We're talking 130 degrees compared to 220 on the other 3. Again, this is when it is idling, at higher R's with a load, I'd say it is running on 6 cyls.

Any thoughts, comments or experiences?

Ed, assuming there are no gross mistakes in the valve train causing this I think your hunch with the injectors is dead on. Poorly performing injectors could cause the mixture to be off in these three barrels. Maybe the short opening times during idle are more affected compared to when the engine is under load. An easy check would be to move an injector from a "cold barrel" to a hot one and see if the problem "follows"

Another thing to test would be leaks in the intake. Get a bottle of starter spray and hit the points where the intake runners meet the head. A leak there could maybe cause effects on individual barrels. (Keep a fire extinguisher close by :D)

The CHT affects mixture in all barrels with the engine below operating temperature. There are several threads describing what resistance you should measure when cold and when at operating temperature. I assume you pulled it with the engine cold and that's why it had such a big effect.

Keep us posted,
Ingo

Run a can of Sea Foam through your fuel system and see if they balance out.

http://www.seafoamsales.com/motorTun...s/image002.jpg

Zoana,
I used sea foam before, on cab cars but never on injector car. Someone said it can burn injectors. Do you know anything about this?

Ingo, you're reading my mind. That is what I think is happening with the injectors.

Tomorrow, I'm getting a can of starter fluid to check the intake for leaks, double-checking the gap on the crank sensor, and pulling the ICV to clean and lube. But, I think the ICV would wreak havoc on all cyls, if that was the case. The fact that I've got the issue on random cyls on both banks would tell me that there are issues at each cylinder. Either spark of fuel related-and I've got spark.

Ed you are correct about the ICV, it would effect all cylinders. Have you pulled the plugs and checked their gaps? Sounds simpe, but I had a similar problem on a motor once, freshly rebuilt, and it turned out one of the plugs had almost zero gap. I guess I had dropped it after gapping and before install.....

Other than that, I would still supspect the injectors.

Cheers

It's the first bullet on the technical properties page:

http://forums.pelicanparts.com/uploa...1197592323.jpg


I know that I tried everything I could to open my piston squirters when I rebuilt my motor, and it only took two drops of the stuff to clear it right up. I'm a fan forever.

I'm running a new set of the Bosch +4's, which are "gapless". I've run them (my old set) for a couple of years, and I love'em.

I'll pull one of the rails and swap two of the injectors and see if I can get the problem to switch cylinders. Due to the fact these were bad enough to not let the engine fully start initially, I'm really banking on the fact that this is the cause.

I don't want to run the car like this, with uneven firing at low R's, on the new motor to allow enough Sea Foam to run thru and do its job, so I'll just send them back up for a rework.

Thanks to all for your input!!!

I suppose I could rig a setup to blow them out, but I've got to be out of town for a week starting next Tuesday, and I can have them back when I get home.

Don't count out the plug wires...

ianc

Rather than Starting fluid (ether) use a spray can of Carb. cleaner. It work much better than ether. (It's also not explosive as is ether)

The engine will stumble with Carb cleaner and idle will increase with ether. I've found that it's easier to detect a stumble than an increase in RPM's.

Since the engine is stumbling so much now, it seems that ether may be a better way to check as I think an increase in R's would be more noticeable.

"I've got low temps on the headers where the exit the heads on 3 cylinders: 1,2 and 5. We're talking 130 degrees compared to 220 on the other 3. Again, this is when it is idling, at higher R's with a load, I'd say it is running on 6 cyls."


Are these the cly. that you where having trouble with injectors working on before?

This is also a "new" motor have you rechecked the Co?

Fernando (socal70rsr) on the board had his injectors cleaned and checked as part of an engine rebuild and then ended up replacing them for all new ones. I think he had a similar issue He has a 3.2 motronic. The new injectors fixed his problem.
Not sure if he posted about it, but we did talk about it.

If you measure a hot cylinder and a cold one and then trade injectors, that might confirm. Do you have access to a wide body O2 sensor to check AFRs out the pipe (but pre cat)?

Doug

The 1 and 2 were two of the ones that didn't fire at first. The #4 was the other one, now it seems OK, and the 5 is stubborn. I can't even think about CO until I get it on 6 cylinders.

That's interesting about Fernando's car.....I hope I don't need new injector$$

One of the things I'm doing tomorrow is swapping injectors from a known problem cyl to one that is working. No wide body O2...

I have seen this problem a number of times when installing injectors that have been sent out for service. I think I have fixed all of the none working injectors by the following method. Put the metal end of a flat tip screwdriver, medium size, on the metal part of the injector and tap on the plastic end of the screwdriver with a small hammer. Do this with the engine running on the cylinders you identified with the lower ex. temps. You will hear the engine sound change when the injector starts working. I have had injectors work with only a few taps, or as many as a dozen.

This may sound like a crude method, but it won't hurt the injector if you use care. The shock treatment seems to work, and I have never had an injector fail to work again when this sticking problem is cured.

Hmmm, thanks Scotty. I may give it a whack (pun intended)

I tried gingerly tapping on them with the plastic handle of a screwdriver, but that didn't give me much"leverage". This sounds like a more positive way to shock them without brute force.

By the way, since the prospect of new injectors may come into play.....and the price can be steep, does anyone know anything about these guys? $269 for a set of 6.....

http://www.fiveomotorsport.com/Injector_SetsPORSCHEVW.asp#bosch59

Thanks.

Ed,
$269 seems paltry given the amount of time and $ spent and the cost of redoing the motor due to low AFRs? In for a penny, in for a pound. May as well make sure your injectors don't crap out when you need them most: at the track. It is not my impression injectors have an unlimited lifespan.

I read that you are moving to Southern California. Email me offline. I'm in Encinitas, which is north county of San Diego (South of Carlsbad, North of Solana Beach). Maybe I can point you around when you are exploring to find the right place.

Doug

Just for fun, what spark plugs are you running? I put in those fancy high priced Bosch plugs and my 3.2 ran like crap.

I agree wholeheartedly about spending the money. The point is these are CHEAP compared to the cost of Bosch injectors at most places, which is usually $120-$150 per injector! I may take you up on the offer, thanks!

I'm running the Platinum +4's....I have for the last 2 or 3 years, they've been a great plug for me in the past.

Ed,

I quickly read the other's posts, but concentrating on your post I'll toss this into the mix.

Pull the plugs and inspect after you let it idle a bit. Are the plugs wet? Carbon? I suspect the injectors are bleeding too much fuel into the cylinder at idle or small throttle opening. When you open the throttle, the additional air masks the problem and the engine runs normal enough.

During a long road trip in my Carrera, I noticed at cruising speed that there was a hint of what some of us might consider to be a miss-fire. When I first noticed it, I opened up the throttle for a bit, and the probelm when away. As I continued on my trip I began to notice the "miss" more and more. After the trip, the the problem got worst. I could tell there was something not right at idle or small TB opening. I tested the ignition and found nothing, but I knew one of the cylinders was not always firing right. I had rebuilt the engine that summer, and was fearful of a broken rocker, so I did a compression test. Every cylinder tested fine, but I noticed the #1 plugs didn't look as good as the others. I replaced it and the problem persisted.

I pull the plug again and noticed it was very wet after the start and idle test immediately after I replaced the plug. I replaced the #1 injector with a used injector from the spares parts collection, and the problem has never returned.

What was happening was that at idle and small TB opening the cylinder was sometimes too rich to fire, but at larger openings the mixture would be right and the problem went away. Spirited driving didn't fix it and only masked the bad cylinder when I pulled the plugs. It sounds like you are experiencing this on more than one cylinder. See if you can borrow some injectors locally to test with. If you can't shoot me an e-mail. I may have some used ones or I can help get you some at a discount.

Side ntoe: I used plain copper NGK plugs and love them. I've had a couple of bad episodes with Bosch plugs butnever with NGK, and haven't considered them since.

Ed, why don't you change around 2 injectors, one that you think is good and one that you think is bad and see if the problem moves around?

Thanks Souk for taking the time to explain your past experience. When I was first struggling on this, it was the exact opposite, the plugs were bone dry with no sign of fuel.

So, now for the update: I tried starting fluid on the intake, and I got a bit of a rise on the #2 and #4 cyls. So I retorqued the intake to 21lbs. It helped a little. I then went out and ran the car a bit. It seemed to get better. Then, I went and filled up with some new 93 octane, and put a can of Sea Foam in it (Ok Zoanas?? ;)) Ran it a bit more.....came home and checked the temps, I've got good cylinder temps on 5 of them, the #5 is a bit low when it gets to idle. They were all at similar temps (300+) when I first came back, however. The idle and part throttle is much smoother, when it's on the lift, and the idle speed is back up to about 750 RPM. I will say that the cam comes into play a bit on the idle, IMO, as the performance cam has a bit of a lope, so it doesn't sound as smooth as before.

So, the Sea Foam did it!!! Just kidding, but I figured it wouldn't hurt. I checked spark again on #5, and it is good. I also rigged up a test light for the injector harness, and it seems to be firing fine. So, I still suspect #5's injector as being marginal.

Now, we've got rain again, but we should clear tomorrow afternoon. So, I'm going to take it out a put a few more miles on it, and see what I get. If it runs right, problem solved. If not, then I'll swap the injectors on #4 and #5 to see if the problem migrates, if the injector doesn't clear. If it does, I think I'll bite the bullet and buy one new injector. I'm not springing for 6 of them at tis point.

Thanks to all, and I'll keep you updated when I get another drive in. I took some video of it running, I'll try and post on YouTube (I've not done that before) and let everyone see/hear.

That's what I'll do next if I don't like the way it drives. The engine was hot when I was messing with it, so I didn't want to crack the high pressure fuel lines on the hot engine.

OK, Porsche lovers, here is video:

http://www.youtube.com/watch?v=f8gl1orKzXM

:D:D:D:D:D

Where did you find that K&N air filter and adapter? Notice any difference after it was installed?

It's basically homemade with high-temp silicone hose. I put it on to clean the engine bay up, I don't know that it's done anything for performance. You can hear the intake a bit when you wind it up...

Another satisfied customer. :D

Do you affraid of sucking in water when it's rain, or car wash?

Not really.....she rarely sees rain, if any. I put a garbage bag over the engine/under the grill when I wash her.

I bought a set from them on ebay for a little cheaper than that. They are not the exact part # as the original 911 injectors (I think they are for a BMW), but they work and fit fine. I'm still running them.

ianc

Thanks ianc, that's good info. Same as the DME crank sensors, 911 parts are $150 per, BMW version which appears to be identical is only about $100 per.

Ed,
What is the wrap up?

Ed, if you got a bit of rise from cyls 2 and 4, and it still isn't sealed, your intake manifold flange could be slightly warped - over torquing the nuts usually does it . If so, you can plane them with some sandpaper on a granite countertop. I'd also replace the phenolic spacers with new ones.

Well, it is "pretty good". I've got about 100 miles on her, but I'm in SoCal for a week, so she'll be sitting a few days.

Steve-thanks for the tip on the flanges, I may pull it and check. The spacers (& gaskets) are new. I used 574 to seal one of the gaskets to the head surface and the other to the intake flanges, but kept the spacers dry, which I believe they are supposed to be.

Sunday, I got a bit of the low end miss again. I checked the intake barrel nuts, and they were most all a little loose. Again, I retorqued to 21lbs (vs 18.5 spec) and drove her about 25 miles yesterday before going to the airport. She was superb. I'm going to see what happens with more miles-basically see if it loosens again. I don't have split lock washers under the nuts, but the "wavy" lock washers which were there originally, I think.

Of course once we move back to SoCal, she gets a date on the dyno with Steve for optimization!