1.3 Motronic Up-Grade & 2.7i How To

[Swanny]

Some issues with the tach and fuel eco gauge. The body harness is going to be missing all the OBC stuff and a few other connectors on the body side are going to be different. Its been a minute since I’ve had to comb through the eta stuff so i’ll keep an eye out and see what else I can find. Please tell me you have your own copy of the ETM though as its much easier to flip and compare.

[MrWolf]

Which harness do you have and what ECU? Its possible with the late harness the injector connection has corrosion causing firing issues. Are you sure fuel is getting into and through the rail?

I had to jump a relay to get my fuel flowing properly in my 87is. Took time with the ETM chasing down wires to get it all sorted out since they're a weird in between model.

Swanny can you clarify. I have a '86 325es, building a 2.7i using a harness from a '87 325i convertible (i think - not positive though). Build is complete but wont start and I'm thinking it has to do with the C101 pins not matching. 12 pins on the harness, 11 pins on the fuse box side.

How can you identify if the injectors are opening? I'm using 19# yellow tops that I refurbished myself, they worked fine when checked with a 9v battery prior to install.

I think my big problem is fuel delivery. My fuel transfer pump runs when jumped, but not with the relay in and the key turned. Relays are good when checked with a 9v, and all the relay terminals checked good with a voltmeter against the Bentley manual. I'm thinking it has to do with the C101 pins. Those electrical diagrams you posted are completely Greek to me. Hoping you can shed some light.

[jeffnhiscars]

Swanny can you clarify. I have a '86 325es, building a 2.7i using a harness from a '87 325i convertible (i think - not positive though). Build is complete but wont start and I'm thinking it has to do with the C101 pins not matching. 12 pins on the harness, 11 pins on the fuse box side.

How can you identify if the injectors are opening? I'm using 19# yellow tops that I refurbished myself, they worked fine when checked with a 9v battery prior to install.

I think my big problem is fuel delivery. My fuel transfer pump runs when jumped, but not with the relay in and the key turned. Relays are good when checked with a 9v, and all the relay terminals checked good with a voltmeter against the Bentley manual. I'm thinking it has to do with the C101 pins. Those electrical diagrams you posted are completely Greek to me. Hoping you can shed some light.

I used a dash bulb (low wattage) between the harness and injector as a test light to see if the ecu was firing the injectors. To test the actual injectors pull the rail and point the injectors at a piece of cardboard. If it gets 6 wet spots they work

[MrWolf]

I've got a 06/86 e (Motronic 1.0 system) that I'm doing a 1.3 upgrade on. I'm ready to swap out the harness and the 1.3 harness fits right on to my stock c101 connector. I know when people had the older square connector some wire splicing needed to be done, but I'm not sure about this.

Do I need to move some wires around or can I just plug the 1.3 harness into the 1.0 connector and go?

I took a photo and there are clearly some pins on the 1.3 side that won't be connected to anything on the 1.0 side.

I think the answer to my question is "Yes" but I'm not sure if I've read about systems getting fried from just plugging and playing. Wanted to be sure before I reconnect the battery.

Been doing some digging, and now after reading this post and its entire 30+ pages twice now, I still haven't found the definite answer. I'm concerned with the same issue that lateracer posted above back in 2010. I've got a near identical setup to his, '86 eta, swapped i head and all necessary parts, using an '89 i harness and 380 ECU, the harness c101 connector fits the body, but the pins don't match exactly. Many have mentioned it's "plug and play" but unlike a few success stories on here, I'm not "firing right up". Here is the engine harness with 12 pins, and the body side with 11 spots.



Does something need to be spliced in here to get it to run? I feel fairly confident everything is connected correctly, but don't know what I am missing. When I turn the key I don't hear the fuel transfer pump, when I jump the fuel relay it fires right up, so pump is good, checked the relays - good, starter engages and engine turns over but it doesn't fire up. I've tried swapping the crank ps and halifax ignition sensor connectors, same results. There are a few wires near the ECU connector that I have no idea what they go to. One brown (should be a ground?) and the other blue/red. Anyone have an idea what these are for?



If anyone who has done the e to i swap and encountered similar issues I'd really appreciate a point in the right direction. I'm so close!

[ATL_E30]

In the very early stages of collecting parts for this. I have a stock 88 325 super eta, so my question is do I need to collect parts for 88+ or can I get an i manifold, ecu, etc from a pre 88?

Thanks in advance!

[ForcedFirebird]

In the very early stages of collecting parts for this. I have a stock 88 325 super eta, so my question is do I need to collect parts for 88+ or can I get an i manifold, ecu, etc from a pre 88?

Thanks in advance!

All you need to change is the valve springs, cam, ecu, inlet manifold and throttle body when you have an 88 "seta"

[ForcedFirebird]

Also, here is a great site for information on swapping your eta to later model equipment...

http://strictlyeta.net/technical/328i_1.html

[MrWolf]

All you need to change is the valve springs, cam, ecu, inlet manifold and throttle body when you have an 88 "seta"

The SETA also used the 200 cast cylinder head - you will want to replace with an 883 "i" cylinder head to make the most of the conversion. The 883 uses bigger intake valves, has larger intake and exhaust ports so it "breathes" better and is where you are going to make the most difference.

The SETA uses the same pistons as the i, but with a longer stroke so the 88 is actually the ideal car to use in this "stroker" build. Replace cylinder head with i head and components, and use an i ECU and wiring harness and BAM! - you've converted your ETA into a stroked 2.7i

All this is pretty well documented throughout the 50+ pages of this thread and on other threads of r3v.

[MrWolf]

Also to anyone following on my previous post regarding the C101 connector - the issue with the mismatched number of pins was not an issue for me. I got my car running with no alterations or hacking of the wiring harness. An 86 eta and a 89 i harness WILL work!

[ForcedFirebird]

The SETA also used the 200 cast cylinder head - you will want to replace with an 883 "i" cylinder head to make the most of the conversion. The 883 uses bigger intake valves, has larger intake and exhaust ports so it "breathes" better and is where you are going to make the most difference.

The SETA uses the same pistons as the i, but with a longer stroke so the 88 is actually the ideal car to use in this "stroker" build. Replace cylinder head with i head and components, and use an i ECU and wiring harness and BAM! - you've converted your ETA into a stroked 2.7i

All this is pretty well documented throughout the 50+ pages of this thread and on other threads of r3v.

You are confused, it's right on page 1!!! Please fact check before challenging a senior member and/or giving advice to other members.

1988 super eta, seta

Parts Needed:
i intake manifold, i 173ecu(computer in glove box)

Optional Parts:
i cam, i double valve springs, i duel exhaust, i radiator and expansion tank, i single fuel pump fuel tank and fuel lines, i flywheel, i transmission with drive-shaft(Must use original center support bearing), i differential(4.10 from ix), i brake booster, i 90amp alternator[U]

I will take the "883" as a typo. The seta does NOT use the same pistons as the "i", as the rod pin was moved to account for the 130mm rods and 81mm stroke (top domes are the same shape, though). If you put seta pistons in an "i" motor, they will stick out of the block ~2mm. Likewise, if you put "I"pistons in a motor with 130mm rods and 81mm crank, the pistons will be 2mm down in the block. I shave blocks 2mm to do this combination often and it results in a 9.5:1 2.7 with all the good things an m20 has to offer. The domed shape pistons in the "i"/seta do not interchange with the 200 head as the eta pistons are flat to match the 200 head flat combustion chamber.


The 1988 seta came with an 885 head, eta 7 bearing cam (200 head has 4 cam bearings), seta-specific manifold, eta TB and seta-specific ecu. Right now in my workshop I have TWO seta engines, 28 m20 cylinder heads in various stages of rebuild, and 8 m20 rotating assemblies in various stages of rebuild. I have owned 14 e30's and opened my shop in 2009 which has about 90% e30 clientele.


Even flowed the 885 head with a seta and stock manifolds on my flow bench. I have dyno tested countless options (my dyno files are in the thousands). Your eta with 885 head will make around 135whp as it sits. A stock tired b25 makes about 150. The seta with an i cam/spring/electronics are in the 165 range. The b27 crank with eta rods/crank and block shaved 2mm makes about 175. Change the crank to an 84mm, they go over 180.

Also to anyone following on my previous post regarding the C101 connector - the issue with the mismatched number of pins was not an issue for me. I got my car running with no alterations or hacking of the wiring harness. An 86 eta and a 89 i harness WILL work!

I did my first eta top end swap over a decade ago on my first e30 (about the time this thread was started), and have done numerous since. There's only one wire you need to worry about in the c101 and that's #20. #20 on some cars are a power, some are ground and some are empty pending production date. Later models have a red/yellow wire, some early brown, some early empty. If you plug a red wire into a brown wire, you will fry the body harness under the steering wheel (ABS relay circuit), and your engine harness will be toast. I have seen people do it so many times, and repaired burnt wiring I don't know how many times.

[ATL_E30]

I appreciate everyone's input here! Very knowledgeable all around! My main question though however was should I be sourcing all of these parts from any e30 or should I be focusing mostly from 88+ e30's.

Reason I ask is because I have an 87 iS as well and if i'm unable to sell it in a timely manner I would look at parting it out and keeping all the i bits needed for this conversion.

Thanks!

[ForcedFirebird]

I appreciate everyone's input here! Very knowledgeable all around! My main question though however was should I be sourcing all of these parts from any e30 or should I be focusing mostly from 88+ e30's.

Reason I ask is because I have an 87 iS as well and if i'm unable to sell it in a timely manner I would look at parting it out and keeping all the i bits needed for this conversion.

Thanks!

Best bet is to just put the whole b25 in your eta. The "stroker" using a flat piston piston engine with 885 head doesn't make as much power as a plain b25.

[MrWolf]

ForcedFirebird, whoops, don't know where I got "883". Apologies for any added confusion. You certainly spelled out your credentials - I've got one project still in progress under my belt, undoubtedly I am the amateur here.

I obviously was confused, so help me understand here. Back from page 1:

"For the 1988 model year, the eta cars got a refresh from the factory. This included a newer Bosch Motronic version with adaptive idle control, a 325i head casting with the larger valves, ports, revised combustion chambers and water jacket, new pistons to fit the 2.7 L stroke with the 2.5 L head, a dual exhaust system and a 5300 RPM rev limit. Though it only made slightly more power in stock form, it could be easily boosted by bolting on a 325i head, a complete 325i intake manifold and throttle and plugging in the 325i engine control unit. Depending on which cam, chip and intake is used, the combination can make over 180 horsepower with the stock compression ratio."

Why bolt on the 325i head onto a SETA block if the two are the same? What, if any, are the differences? It makes sense that Kenika65 says to do this swap with the SETA you only need the intake manifold, TB, and ECU, but later says bolt on the i head to boost it? Why bother?

And ForceFirebird, do you have a picture depicting which pin on the C101 is the #20? I guess I got plain lucky I didn't fry mine when plugging it up. I do have an issue overall with my setup, the engine revs will fluctuate when warmed up and the gas pedal is down, suddenly cutting out and recovering. Haven't identified the problem yet, wondering if it doesn't have something to do with my wiring. If I can't figure it out soon I'll have to take it to the local indy.

[ForcedFirebird]

"For the 1988 model year, the eta cars got a refresh from the factory. This included a newer Bosch Motronic version with adaptive idle control, a 325i head casting with the larger valves, ports, revised combustion chambers and water jacket, new pistons to fit the 2.7 L stroke with the 2.5 L head, a dual exhaust system and a 5300 RPM rev limit. Though it only made slightly more power in stock form, it could be easily boosted by bolting on a 325i head, a complete 325i intake manifold and throttle and plugging in the 325i engine control unit. Depending on which cam, chip and intake is used, the combination can make over 180 horsepower with the stock compression ratio."

Why bolt on the 325i head onto a SETA block if the two are the same? What, if any, are the differences? It makes sense that Kenika65 says to do this swap with the SETA you only need the intake manifold, TB, and ECU, but later says bolt on the i head to boost it? Why bother?

And ForceFirebird, do you have a picture depicting which pin on the C101 is the #20? I guess I got plain lucky I didn't fry mine when plugging it up. I do have an issue overall with my setup, the engine revs will fluctuate when warmed up and the gas pedal is down, suddenly cutting out and recovering. Haven't identified the problem yet, wondering if it doesn't have something to do with my wiring. If I can't figure it out soon I'll have to take it to the local indy.

The head castings are the same. The 88 eta got single valve springs and a 7 bearing eta camshaft. It also got a seta-specific intake manifold that has the skinny runners and TB like the eta, but the ports open up right at the head.

I don't have a pic handy, but if you peel back the rubber boot the numbers are next to the pins (also on the face side when unplugged).

What AFM did you use? The eta AFM doesn't work properly with the 325i electronics.

[thejimlab]

Are the pulleys necessary?

I've got an 84 325 and I'm in the process of gathering parts. Are the pulleys really needed? Why?