348 Crank Sensors

Nice! I am going to copy this post!

 

>> balanced the vacuum on both banks, checked the fuel pressure (both bang on the same), cleaned throttle bypasses and set the idle and throttle opening synchronization.

Could you elaborate a bit on these operations.

How did you balance the vacuum?

What equipment did you use to check fuel pressure?

Cleaned bypasses using what type of cleaner and tools?

How to set idle and throttle sync?

These and the spark plug deals are the only things I didn't do. I think that the spark plug wire balancing may not make any difference, as it is my understanding that the resistance at the gap goes sky high in the cylinder not under compression, but then again that may not be true at all. Just something I recall reading somewhere. Anyone have more authoritative information?

 

Picked them sensors up today at the local KIA dealer. 523 SEK for both........which is roughly 65 USD.

Fair enough from my point of view.

//B//

 

To balance the vacuum you need a differential manometer good for up to 5 bar suction - I bought one on ebay for $150. You can use a mercury column, or an "U" gauge which are cheaper, but much harder and toxic to use...

Warm the engine fully (on the oil temp gauge) and then disconnect and plug all the vacuum and idle hoses going into the intake manifold. Then connect each side of the differential manometer to a vacuum nipple each of the manifolds. Loosen the bolts on the throttle bypass screws and close them fully. Then open the one which shows the lowest pressure until they are balanced. If the RPM is below 950 rpm, then adjust the opposite side to 1/2 the difference between the current rpm reading and 950, then adjust the other side to balance, which should result on a 950 rpm reading. Tighten the bolts up while holding the screws steady with a screwdriver. Re check the balancing. Then push the throttle at the cable connection till 5000 RPM slowly and make sure the manometer still shows it all to be balanced. If not, you will need to adjust the throttle linkage screw to ensure both throttles open and close at the same time and by the same amount, then hook everything back up. - You have now balanced your intakes and idle point and throttle synchronization.

To clean the bypasses I took the throttle bodies off the plenums, then the bypass screws out. I flushes the whole thing in brake cleaner - done...

Fuel pressure... I bought an extension to the fuel line connection which has a threaded hole on the side. I modified a standard fuel pressure gauge with a fitting that allows me to connect it to the fuel line extension. Start the engine, rev up a few times (you should see a variance of pressure as it is balanced against the inlet manifold vacuum), then let it idle and record the pressure. Switch the engine off and record the pressure immediately after switching off, then for every 30 seconds for 2 minutes then after 10 minutes. This should be the same for both sides, but in the first 30 seconds there should be hardly any loss of fuel pressure than the reading immediately after switch off... If the pressure is too low with the engine on you may have a fuel pump problem or regulator problem. If it is too high you have a regulator problem (and probably a whole lot of other fueling/emissions problems as the fueling curves assume a 3.8 bar operating pressure. After switch off if the pressure drops quickly you also have a pressure regulator problem.

 

I am going to save this page for future needs.

Great!!!!

//B//

 

Yes Marco!! Thanks so much for filling all that in. If one has to adjust the throttle plates is the service manual procedure adequate?

 

I found this in a patent application filed by Messrs. James G. Friedline and Leo G. Rich. I had it wrong, but the conclusion is the same. Basically what it says is that of the spark plug wires, one is connected to one end of the secondary coil and the other is connected to the other end. Thus they are in series, not parallel, so minor variances of resistance between pairs does not affect anything. On the other hand, by balancing all 8 spark plug wires, one might conceivably achiever smoother running.

Again, Thanks Marco! Where were you when Ferrari was writing that weak service manual?!

 

yeah - this is good stuff!

 

Thanks... Many times I think I can afford more precision with my time as I am motivated by passion and not by profitability. The workshop manual has a perfectly adequate procedure. I believe mine is better for me as I have adapted it for a differential manometer (can't get an U gauge to save my life) and wanted to make sure it was perfect, so that if something else went wrong, I knew I could build future diagnoses based on known constants (what I have done myself) instead of assumptions.

Besides it all I came up with this before I got a hold of the WSM and developed it by reverse engineering the intake system. So all in all it is a bit over the top as there is some redundancy in the steps, but not far off and also a fun learning experience...

On the point (in earlier posts) of differing resistance readings of the crank position sensors between Kia and Bosch, let's not forget that these devices are induction coils. When the when the crank teeth pass by the magnet they induce a magnetic pulse from the central magnet onto the coil filaments - this pulse is electromagnetic, meaning that in the coil it will travel as an electric current pulse with a frequency directly proportional to the frequency and amplitude of the teeth passing by the sensor.

Basically it has three references, short signal, long signal (reference for Cyl 1 TDC), short blank...

The resistance is somewhat irrelevant as they are all designed to produce a reference current of a given value. The resistance is based on the length of the coil filament and that in itself is directly related to the magnets gaussian value (strength).

You'll find variances between metal cased and plastic cased ones as well as between the same part numbers of the same manufacturer.

M

 

We all know that the Motronic system can drop to open loop when the oxygen sensors drop off line. In open loop the mixture is set with the CO screw on the MAF. The "factory" 383 ohm setting is quite rich and can cause CAT overheats. If your CEL bulbs are disconnected or burned, you may not know you have gone to open loop.

How do we avoid that turning into more damage elsewhere? I tune my MAFs to idle stoichiometry and then a slight bias towards rich. How to do this?

http://www.ferrarichat.com/forum/showthread.php?t=202083

 

So yo blow one and are faced with 5-600 USD bill for a recored one if you can find one... I found a way to cross connect them (Mondial t/348/355 with Motronic 2.5 and 2.7) so the ECU of the bad one reads that of the good one... Have a peek, I lived like this for over 3 months with no problem...

http://www.ferrarichat.com/forum/showthread.php?t=202441

Also have a look at the threads I have started on how to make your own hyperflows and other interesting gearbox bearing and electroncs related stuff I learned the hard way, such as reverse engineering the whole emission set-up and backfitting it to a pre-cat Mondial t from 1989 (but lost no power whatsoever)

M

 

I agree about the variances. The data I located was from Airtex's website. The resistances that they quoted for any one model of sensor had quite a range of in spec resistances between low and high. However in comparing the Kia model sensor (approximate match) vs. the Bosch model (exact match) I saw quite a difference even though there was an overlap. The Bosch model did allow for much less variance than the Kia model. I suspect that the FI used by Kia, a slightly more recent model than the 348, is more robust than our "early adopter" Bosch 2.7s. That is what concerns me. With that much of a range allowed for the Kia model, as well as a higher maximum resistance, I would not be surprised if, for example, an amplifier transistor became overstressed by the differing electrical characteristics of the Kia model and failed somewhere down the road. Probably way down the road, but still. I'll say this one last time and then drop it: for $160 each, to get a genuine "Made in Germany" part from a company that has the consideration to publish pertinent technical information on the web, that the others including Bosch can't be bothered to do, my money is on Airtex, every time. They simply impressed me as having integrity, and that is worth a lot to me.

 

Hey Marco - Great minds do think alike!! I did the exact same mod to my cats, and had not read any of your posts before getting fired up to do it. You took a more scientific approach - all I did was go online and google "metalic Catalyst". When I found those Magnaflows selling for $100 each at Performance Peddler, I figured I had a winner. I then asked a well-respected exhaust guy here in the Bay Area what he thought, and he told me that they wouldn't make much difference, but he'd weld them up for $250, and it was on. BTW he said pretty much the same thing you did about the 2 by 2" pipes - more than enough. He didn't have numbers like you do, just 20+ years of experience working on about everything. Last time I was down there a big truck rolled up with a 1953 Alfa Romeo 1900 CSS Ghia One Off getting the Pebble Beach treatment that needed a new exhaust made.

Pics of the Ghia: http://www.alfabb.com/bb/forums/654947-post1350.html


I am working on creating a custom exhaust system also using Magnaflow components that will fit Mondial ts and 348s. Like you said, I don't expect any performance gains - what I am looking for is a particular sound. It's my variation on a design that a guy from Texas came up with for his 328 Mondy and had the elves at Norwood fab up. It sounds perfect. Not too loud, but a nice deep tone. The Mondial t stock exhaust is too "buzzy" - no soul. It's quite a trick to fit that design into the 348/t's layout, but I think I have a solution. We'll see...

 

does this part work on 95' 348 spider 2.7 bosch?

 

yes. quick tip, The top bolt is a pain with the belts. You can get to it from the passenger wheel well with the fender liner out and a long 1/4 extension and swivel bit much much much easier.

 

sweet. thanks! my 5-8 is pooched