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1995 940 turbo-new volvo guy. Auto trans, camshaft and ECU "theory" questions.

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claytonsmith

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Jan 12, 2020
1995 940 turbo-new volvo guy. Auto trans, camshaft and ECU "theory" questions.

Hello all,

This may be a little verbose. Thanks to anyone who makes it all the way through.

My name is Clayton. I'm not new to cars ( or turbo cars,) but I am new to Volvo. I bought a 95 940 turbo yesterday. It has 265K miles on it and I'm floored by how well it drives and the condition it's in. I drove it 5 hours home and it didn't hiccup, fart or protest in any way.

My experience ( and knowledge base, familiarity) with turbo cars has generally come from a world where speed density tunes, via stock GM ECM manipulation, or various stand alone systems are "the way." I'm learning that these redblock cars are 100% MAF dependent and I have to assume that the factory tables ( at least the spark table) are pretty conservative. I gather the stock ignition table is used with some degree of safety to some degree of modification level. Looking at dyno graphs from stock computer cars, it seems that the factory timing curve really knocks the timing out of them until you're past 3K rpms. Even then, the timing curve seems pretty soft in factory trim.


Do these things use knock sensors to pull out timing or are the timing tables static and locked into whatever they are?


It seems like the trend with these volvos is to make power using better breathing parts at lower boost levels rather than just turn up the wick and rely on fuel and spark manipulation ( on stock cam, turbo) to make them live. That's a little different than I'm used to. I'm learning, though.


I'm cool with that. I'd rather let a motor breath from good cam and turbo selection than rely on cramming super heated air into it and tune it on a knife edge to make it live.



With all that being said, I have some questions.



I'm reading through the redblock cam data thread. I'm used to reading "'Murica!" cam cards, but I'm making a bit of sense out of the euro stuff. The thing I can't seem to source info on is WHAT the cams came in. What year/trim/body style came with what factory cams? Is there a source for this info? Is the K-T-A etc nomenclature directly indicative of a motor code? Does the K cam come in the "K" motor?


How aggressive of a cam have people gotten away with on a stock converter auto car without it trying to push through the converter/brakes at stop lights?


What are the auto trans upgrade options. I believe my car has an AW71? I've read up on the accumulator mod. That makes sense with respect to longer trans life and faster shifts.


What about converter options? The converter in my car is pretty tight. If you get it up on the foot brake it only stalls to about 1200rpm or so. I'm theorizing that 2000-2500rpm converter ( maybe even 3000 with the right cam) would make this an entirely different car.



I have no delusions of this being a race car. It is intended to be a very mild street driver. The AC works and the interior is nice. I really just want to get it to where I can jackass around and it will light the tires at will. That's really the only goal. Jackassery.

Thanks for any info provided!

Clayton
 
claytonsmith said:
Hello all,


Some input in red below



This may be a little verbose. Thanks to anyone who makes it all the way through.

My name is Clayton. I'm not new to cars ( or turbo cars,) but I am new to Volvo. I bought a 95 940 turbo yesterday. It has 265K miles on it and I'm floored by how well it drives and the condition it's in. I drove it 5 hours home and it didn't hiccup, fart or protest in any way.

My experience ( and knowledge base, familiarity) with turbo cars has generally come from a world where speed density tunes, via stock GM ECM manipulation, or various stand alone systems are "the way." I'm learning that these redblock cars are 100% MAF dependent and I have to assume that the factory tables ( at least the spark table) are pretty conservative. I gather the stock ignition table is used with some degree of safety to some degree of modification level. Looking at dyno graphs from stock computer cars, it seems that the factory timing curve really knocks the timing out of them until you're past 3K rpms. Even then, the timing curve seems pretty soft in factory trim.
OEM Turbo ignition map is way over advanced and the result is that it lies riding on the knock sensor almost constantly, not a good scenario when it comes to coping with transients

Do these things use knock sensors to pull out timing or are the timing tables static and locked into whatever they are? Tables are what they are and static per se...The knock sensor is working overtime for sure when hitting boost


It seems like the trend with these volvos is to make power using better breathing parts at lower boost levels rather than just turn up the wick and rely on fuel and spark manipulation ( on stock cam, turbo) to make them live. That's a little different than I'm used to. I'm learning, though. Lower compression, better fuel (E85) and definitely bigger turbo if large power gains are wanted. The cam should really work together with the turbo size, less backpressure from turbine let you choose a hotter cam and vice versa.


I'm cool with that. I'd rather let a motor breath from good cam and turbo selection than rely on cramming super heated air into it and tune it on a knife edge to make it live.



With all that being said, I have some questions.



I'm reading through the redblock cam data thread. I'm used to reading "'Murica!" cam cards, but I'm making a bit of sense out of the euro stuff. The thing I can't seem to source info on is WHAT the cams came in. What year/trim/body style came with what factory cams? Is there a source for this info? Is the K-T-A etc nomenclature directly indicative of a motor code? Does the K cam come in the "K" motor?
The cam naming regime was done at nigth with blindfolds... All stock cams are pretty conservative stuff by todays standards.



How aggressive of a cam have people gotten away with on a stock converter auto car without it trying to push through the converter/brakes at stop lights?
All stock cams should cope with the loosest OEM converters (2200-2500 stall)

What are the auto trans upgrade options. I believe my car has an AW71? I've read up on the accumulator mod. That makes sense with respect to longer trans life and faster shifts.
Accumulator mod is mandatory

What about converter options? The converter in my car is pretty tight. If you get it up on the foot brake it only stalls to about 1200rpm or so. I'm theorizing that 2000-2500rpm converter ( maybe even 3000 with the right cam) would make this an entirely different car.
My stock converter (95-940 with FK engine stalls 2200 )


I have no delusions of this being a race car. It is intended to be a very mild street driver. The AC works and the interior is nice. I really just want to get it to where I can jackass around and it will light the tires at will. That's really the only goal. Jackassery.

Probably need a modified converter for that, at least from standstill


Thanks for any info provided!

Clayton
Click to expand...


Filler
 
Thanks for the input mrjaybreeze! I had some follow questions to your responses.




OEM Turbo ignition map is way over advanced and the result is that it lies riding on the knock sensor almost constantly, not a good scenario when it comes to coping with transients

Good information. Not a good scenario, as you mentioned, though. Hah. Noted.

Tables are what they are and static per se...The knock sensor is working overtime for sure when hitting boost
Noted again. I gather these ignition computers are referred to as "EZK" and I see at least some mention of the timing tables be alter-able. I'm assuming fuel and spark data for the respective computers lives on an Eprom chip?

I don't see many "companies" offering tuning services. Are there any recommended members that burn chips with proven good tables? Does the ability to make real-time changes via something like an Ostrich emulator exist? Or is this a burn, install, test, reburn, reinstall scenario? I don't mind using a proven turbo, cam, exhaust "recipe" if only canned, burn-and-mail, type tunes exist.
I'm assuming the factory eprom must be desoldered and a zif socket ( or similar) has to be added for repeated insertion/removal of the eprom?


Lower compression, better fuel (E85) and definitely bigger turbo if large power gains are wanted. The cam should really work together with the turbo size, less backpressure from turbine let you choose a hotter cam and vice versa.

Noted. The standard turbo car approach, then. Regarding E85- has anyone integrated a flex fuel sensor ( are the lh2.4 computers even capable of real time alteration to fueling tables beyond whatever "normal" capabilities are there for running with a stock o2 sensor in closed loop) into the stock computer to deal with the alcohol percentage fluctuation in pump e85? Or are we talking containerized, non-pump e85 here?


My stock converter (95-940 with FK engine stalls 2200 )

Interesting. Mine doesn't seem to want to footbrake stall past about 1200. That's not necessarily an indicator of the converters stall speed, though. It could just be pushing past the car's brakes. Regardless, it seems like it could really benefit from one that will flash to the 2500 range with sudden throttle application, off the brakes. I'm assuming no one makes aftermarket converters? Perhaps a converter shop will re-stall one.


Thanks again! It's refreshing to get good answers. I'm used to Honda and LS forums where people just make grunting noises and post stupid memes as opposed to typing out clear, coherent information.
 
Last edited:
The cam codes are stamped into the back of the camshaft. If you're looking at switching to a different OEM cam, your best bet is to probably just post in the wanted section: "Hey, I'm looking for a slotted A or B or V or whatever". In the US the 900 series cars got only the M in B230F (n/a) and the T in B230FT (turbo) applications, so finding something other than that in a salvage yard will be next to impossible. Bear in mind that your 900 series car uses a rear-of-the-head mounted distributor, and as such the cam is keyed to drive it. Cams that come out of 200 series cars do not have the slot and are not compatible. Aside from that, they are identical.

Real-time Ostrich works. We dyno tune and then burn a PROM.
 
Look around mrjaybeeze's site: ipdown.net/jetronic.info/tiki-index.php
and you'll find .bin EPROM files for various factory LH ECU (Fuel Control) boxes, and EZK (Spark Control boxes), plus info on editing and Ostrich use, for example: https://ipdown.net/jetronic.info/tiki-index.php?page=Ostrich%20Install

Compared to modern tuning software, the TunerPro package for the EZK/ECUs is pretty primitive. Along with each eprom image file is a .xdf file. The .xdf was made by someone talented who figured out where the basic tables are in the eprom image and how they're scaled. Real time logging is not generally available, other than what you can do with an Ostrich.

At to top of the "Maintenance" section of this forum are a couple stickied threads on where the documents from old websites have migrated to. The "greenbooks" are green covered Volvo factory manuals. Find a copy of "Volvo TP 31397-1 Ignition.pdf", or something with TP31397 in the name, and it will explain the spark/knock control algorithms.

Converting to MegaSquirt or MicroSquirt is fairly common here, and linuxman51 sells conversion harnesses/kits to go from the factory LH/EZK connectors to MicroSquirt.

For chips, a couple member sell/support them - sbabbs / thelostartof (TLAO for short). Chips are usually for bigger turbos, better exhaust flow, and higher RPM limits. All the LH2.4 ECU boxes use socketed eprom chips from the factory. Some of the EZK boxes use socketed eprom chips from the factory (e.g. gold colored ones from 740/940s), and others can be converted to chipable by adding an eprom daughter card.
 
bobxyz said:
Look around mrjaybeeze's site: ipdown.net/jetronic.info/tiki-index.php
and you'll find .bin EPROM files for various factory LH ECU (Fuel Control) boxes, and EZK (Spark Control boxes), plus info on editing and Ostrich use, for example: https://ipdown.net/jetronic.info/tiki-index.php?page=Ostrich%20Install

Compared to modern tuning software, the TunerPro package for the EZK/ECUs is pretty primitive. Along with each eprom image file is a .xdf file. The .xdf was made by someone talented who figured out where the basic tables are in the eprom image and how they're scaled. Real time logging is not generally available, other than what you can do with an Ostrich.

At to top of the "Maintenance" section of this forum are a couple stickied threads on where the documents from old websites have migrated to. The "greenbooks" are green covered Volvo factory manuals. Find a copy of "Volvo TP 31397-1 Ignition.pdf", or something with TP31397 in the name, and it will explain the spark/knock control algorithms.

Converting to MegaSquirt or MicroSquirt is fairly common here, and linuxman51 sells conversion harnesses/kits to go from the factory LH/EZK connectors to MicroSquirt.

For chips, a couple member sell/support them - sbabbs / thelostartof (TLAO for short). Chips are usually for bigger turbos, better exhaust flow, and higher RPM limits. All the LH2.4 ECU boxes use socketed eprom chips from the factory. Some of the EZK boxes use socketed eprom chips from the factory (e.g. gold colored ones from 740/940s), and others can be converted to chipable by adding an eprom daughter card.
Click to expand...


Awesome info and direction for my own data gathering. The tp31397 was very helpful. That's gonna get stored for later reference. Thanks for all the good info!
 
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