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

[efhughes3]

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?

[ischmitz]

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 )

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

[ZOA NOM]

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

[rnln]

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?

[efhughes3]

Originally Posted by ischmitz

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 )

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

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.

[Jeff Alton]

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

[ZOA NOM]

Originally Posted by rnln

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?

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




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.

[efhughes3]

Originally Posted by Jeff Alton

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

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.

[ianc]

Don't count out the plug wires...

ianc

[ljowdy]

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.

[efhughes3]

Originally Posted by ljowdy

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.

[911quest]

"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?

[DW SD]

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

[efhughes3]

Originally Posted by 911quest

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?

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.

Originally Posted by DW SD

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

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...

[rsscotty]

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.

[efhughes3]

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.

[efhughes3]

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

[rnln]

Thanks.

Originally Posted by ZOANAS

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




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.

[DW SD]

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

[cgarr]

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.