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Escort Cosworth EEC-IV 2.0 Turbo ENGINE FAIL (finding reason)

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Hi guys!

as first...thanks for every your opinion..

Since, there is no topic for engine fails :D ....I put it into general.

I Have strange story with one Cosworth small turbo EEC-IV

Start when timeline begins...

Car was bought in Holland, 2 years ago, unknown condition with customer without any

technicall knoweledge about. (Car was starting, moving...etc)

It was parcitally rebuilded by some unknown garage in our country ( skimmed head, rebuilded head and some unknown basic things...)

Customer wants to put all tweaks into engine which he found over internet....

So garage put some racing camshafts, T35 turbo from bigturbo cossie, fuel pump, inlet plenum spacers, new custom exhaust, custom exhaust manifol, re-drilled and polished

thorrtle body...double springs on valves, some superchip/powerchip eeprom for external J3 port of EEC-IV ecu. Some tuners want to play with ecu

offcourse without luck, cause that intel eeprom inside ecu is almost not readable...etc etc...

Done....then car didnt want to start...logically...

Then customer found me...I am working little with cosworths in our country (but you know 3/4 cosworths are management IAW P8/L8 ECUS)

And he was helpless cause since I know that EEC cossie is only one in our contry and almost nobody understand what is going on.

I ordered customer to remove that racing camshafts, buy new hego sensor...so car was able to start and move..

he came 300km to me.

We order all necessary HW to mod that EEC-IV ECU. Binary editor with dongle, moates quarterhorse, strategy definition for GHAJ0 type.

All looked ok.

Job was ordered...put som power into that car...it is very lazy.

Ok, we put little bigger injectors (380cc bosch)

very fast I found that something is not right.....

I sorted injector slopes hi and low (that is value of injector capacity, ecu is then calculating how much pw needs to achieve AFR).

but AFR was still 14-15 under high load... there was several ways how to cheat it...edit MAF transfer tables...move injector slopes...

but that was no way ..I want to fix it..not cheat it.

After few weeks and external help, logs from friends EEC-IV cossie from other side of the world I found that 20 years old MAF sensor is cheating,

it was showing that less air is going thru (less than reality was)...ok, where to find cosworth EEC MAF? all stuff is 20+ years old..quite problem for MAFs..

after some catalogue researching we found that electronic part of maf is same for almost every EEC-IV in that years, only housing is changed to measure smaller/bigger flows.

hua! I ordered new MAF for 1.8i XR3i escort, get sensor, put into cosworh housing! Boom...now engine was reading right values on idle, it was accelerating good with AFR 11-12 directly as AFR map was ordering.

I precisely tunned injector slopes to fit real AFR into ECU AFR command...almost done! ECU command LAMBSE was almost same as real AFR (innovate LC2 with direct logging into ECU logs) so I had all data in one software and one log.

Other problem came into...It was hitting 100% injector duty cycle very fast...with very low boost..feelings? not very much power..almost 400cc injectors? fuck! it has 220hp with some 280cc injectors...and with simple boosting OEM injectors it can reach 270 hp.. (other cars).

ok...customer wants car (2-3 months car was here...repairing some wiring issues, fuel pump wiring and other cosworth related fauls).

so I tunned fuel to be good AFR, made boost amal valve PW to keep boost low in higher RPM ..cause I dont want to hit 100% duty of injectors.

During test rides I found that engine is little fighting itself over 5500rpm...it was little refusing going over...I told customer that something must be wrong

inside engine cause any timing of fueling has no effect on that. He told me that engine was rebuilded and it is 100% ok..

I inform customer that engine is eating oil...after 300 km done by me it eated 1l of oil..and it is not good!!!

He told that it is ok, he know about it..you know when you rev it a little..it is eating oil... aaah ok...engine needs to be inspected!!!

no no..it is ok...

He grab the car.....car was running good, ofcourse until 5500rpm. Dyno shows 240hp, with significant fall of power over 5500rpm.

The fun started again

Now I inform customer that we need do some research why there is such problem...

boom, engine tming on CID sensor was bad about 30° away (CID sensor - Cylinder ID recognition), it is hall sensor with 180° sensing. so Ecu knows about every 180° cycle of engine) as from docs, this is helping ECU to sync fuel.

OK, sorted CID sensor align..

AFter starting...fueling was very bad, car was rich on idle...so I need to touch injector slopes to get fueling right (ECU command = real AFR), done.

Now I can boost 2x more....with 90% injector duty. we have about 1,2 bar over 4000 rpm without problem...car now has significant power!

So I sorted boosting (cause ecu is calculating fuel automatically based on MAF and boost)....

One issue stays...that engine fights in high revs....now that fight moves over 6000rpm..not affected by engine load...it was fighting always in every 6000rpm situation...ok something must be wrong....

I decided to check what real ignition advance on car is (cause here ECU is not commanding advance directly...timing is done by EDIS module, which is only receiving PWM command from ECU how advance should be). So I put car into garage....and start measuring commands for coils...bla bla bla.

then bum bum.....rear conrod bearings was turned....piston starts to kick a head little...done!

Engine on desk...photos in attachment

So guys ...thanks for reading.

I know lot of mistakes was done from my side...lot of mistakes was done before on engine...who knows what was done on that engine by previous owner...nobody knows.

That is not proble, customer is a good man...I want to help him sorted it, cause there is not much people here which can be able sort it.

Questions are!

Why it happens? Oil black like a night...pressure was still good (there was racing oil pump with higher pressure).

Wee need to learn from it! Thanks a lot again.

Attached Files

Just guessing here. Maybe too much fuel dilution in oil / bad condition oil. And a bit of detonation or misfiring because of the high RPM issue caused the bearing to get hammered and wear out.

Sounds like the car had alot of tuning over that time. At no point in there did you mention having the oil changed. And at the end you say oil was black like the night.

It looks from the pictures at least that the number 1 or number 4 cylinder(the one with the shinier piston top) was running a bit lean. Have you checked all injectors are firing correctly and signals to them are good?

It is possible too that during the initial weird MAF readings it may have caused damage, running lean without realising at a lower hp, and now with more boost and more hp that problem is highlighted?

Your injectors sizing as well seems a little small, I have only the 4g63 to go off but at 15psi I'm running 450cc injectors and that is just enough before the injectors I have at 5500rpm to hit fuel cut and max duty cycle. ( Car has vac issues as well so that's contributing, but still seems a little small in size)

I'm just guessing at this point, but why not, good luck with the build and the diagnosing.

Could also be the engine builder mucked up that rod cap torque... Hard to say if you don't know.

First of all, the customer brought you a basketcase car. You had to clean up somebody else's mess. So don't feel too bad about that. The engine may have been on its way out alreayd.

Second, I agree that the injectors were too small from the beginning. I would have had the customer buy injectors with known settings to use such as injector dynamics. You could have contacted ID and told them what you have, and maybe they would give you Mustang SVO injectors (2.3 turbo engine offered in the 1980s) or something else that would fit. They usually include the slope values to use. Once the injectors are known to be big enough to handle the airflow, and the slope values are known good value, you could figure out the MAF sensor housing and sensor electronics next and then scale the MAF sensor.

Ray is dead right - someone else already had a shot at screwing it up and without your actually stripping it down and checking, you don't know what you were actually dealing with - especially once the client stuck their thumb in. That is why, even as a 'prentice, I hated, hated, hated taking over a re-build - you don't know how well the previous person did the job.

As far as the engine is concerned, I would say those are standard OEM pistons so there is a potential problem there if the bore was worn and there are certainly some wear grooves that match the piston skirt markings... even assuming the "builder" actually bothered to re-ring them and the lack of hone marks underlines that. There was also some apparent valve to piston contact at some time.

Main bearings are also marked and that implies contaminated oil - could have been a poorly cleaned block (if the work was actually done), could have been the filter not catching all the debris picked up by the pump and/or the bypass opening? What markings are on the bearing shells - it is even possible they are stock Pinto ones and totally useless in this application.

I didn't notice mention of fuel pressure and whether it was referenced? OEM stuff will usually have limited headroom so need replacing as a matter of course.

Guys thanks for answers...yes primary job was to do custom tune based on logs (not stupig power chip which is simple disable waste gate and cut 0,01 AFR at top)

At the end...it is car rebuild....

But I have understanding to customer..he doesnt have options...If there will be good engine builder...he will not know anything about cossie and EEC-IV. Nobody will spend months to study and learn systems when 1 piece of car is in that country :D :D

And cosworth is my passion...

Into car...

Yes I am cleaning that somebody else did wrong....Its not about that, its about how to solve it and make that car 101%.

Simple issues are not for us :D it will be very easy....

Sorting high-level issues is aducational...and in that world, we are learning every day. Cause nothing and nobody can prepare you

on all in engine world.

Engine oil was changed 2 times after that "engine rebuild", last time it was changed when car was going 1st time to me.

Valve marks on pistons....so..I never saw cosworth engine without piston marks from valves...thats the cosworth standard, who knows why?

My both cosworths had it when I first time open the engine... so I dont know when valves hit it?

4th piston hit a head little cause con-rod bearing fault..thats clearly visible.

Why are pistons washed on intake and exhaust side? When engine was 1st time rebuilded they cleared pistons (not much, but removed carbon).

In my hands, it was never rich and lean...I was very very very precise about it!!! And..that EEC-IV is very clever at closed-loop mode and it can do very big adaptation of fueling to achieve 14,7!!!!

I never run at 9 AFR under load or something....

Injectors are BRAND NEW...not tested ..sure.

yes...too small but that cant be an issue, OEM is about 280? and can be up to 270HP? Customer wants little over 300...nothing more.

Propably I will get bigger ones, siemens deka 60 ...but primary object is make it safe...

Previous garage dint touch the block...they only touch head...

Today I gave whole engine parts to company which will rebuild head again, rebuild crank, block, con-rods...etc.

Guy measured block and you know what? only some 0,06 + -roundness, he said that cant be reason to burn oil!

But he said that honing was very smooth..almost polish...so maybe that was reason?

Oil pump in attachment...

oil pump can be just result....not cause

There is question about ignition advance...that ecu has very small advance from OEM...it was around 6-10° under load..what you think about it?

Attached Files

Ah, it may be that they have very shallow valve cut-outs in the pistons as standard - not that familiar with the engines of late and assumed they would be deeper, if an OEM feature.

oil pump damage not unexpected as any crap in the oil has to pass through it before getting to the filter - what I meant was the marking on the main bearings must have been caused by debris that was either in the oilways from the start or was from the big end bearing failure and wasn't caught by the oil filter.

For the most part, an engine is just an engine - some have peculiarities but they're basically the same. It would seem the person doing the top end might not have been as careful as they should have been, maybe they were - hard to say now.

There is a chap building a Sierra with a YB in the Member Introductions forum - he should be able to give some help and advice, if you need it.

Theory....it has very small ignition advace from OE...And I didnt touch that table.

So it has about 6-9° BTDC advance when peak load and peak rpm.

Maybe it has no time to burn all fuel, and fuel is going thru rings into oil?

We found that washed pistons on exhaust and inlet side can be due to valve overlap and fuel going into exhaust, then burn inside turbo.

question...the roundeness is about 0,06mm shoul it be rebored? cause engine eated oil...but this is not too much....hmm

Low spark advance from the factory indicates that it is highly knock limited cylinder head or compression ratio, or it has a fast burning head, or it's running high temperature or high pressure. Is that spark before or after knocking retard? Was the knock system active?

that ECU does not have knock system ....think that is reason..

but we have a lot of fuel unburned causing propably high temp in exhaust.

We usually reply within 12hrs (often sooner)

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