Blacktop Beams Rough Idle Issue

[csr083]

Hi, there

First post here.

Let me introduce myself - my name is Anton.

I've installed 3sge into the e30 BMW, and everything is awesome - it pulls, revs, and on top of that gives about 35-40 uk mpg.

The engine is a blacktop 3sge (yellow label says G1), coupled to J160 box. Harness connectors are standard for A and B, and custom made for D and E. O2 sensor wire is shielded. Outside temp sensor and oil pressure sensor are disconnected.

The problem is the following:

very rough idle. Rough as engine vibrates like mad. It gets better when its revving, motorway cruise is also good - pulls strong and gives good fuel consumption.

The following things have been checked:

1. Air

All the vacuum lines have been checked (including brake servo), every single doubtful joint resealed and then put together. Vacuum gauge shows no evidence of severe vacuum leaks (that may cause such a horrible vibration).

Engine also uses shed made intake system (cannot fit altezza box in the engine bay). Thought that silly cone filter may cause this, removed filter - no result. AFM has been replaced with a brand new one - no effect. shows very steady 1.2V (checked with a scope) with fluctuations of 0.005V. Toyota manuals specify 1-1.5V AFAIK.

Drive by wire throttle body has been replaced with a second hand unit - no effect

2. Spark

I had leaking head cover gasket and initially thought that this might be it - a dead coil causing misfire and vibration, but no - replaced gasket and coil packs with second hand units (revised thinner COPs) - no effect. Spark plugs have been replaced - no effect. IGT and ION signals are verified.

3. Compression

14 bar at closed throttle cranking - super even and steady

4. Fuel

Fuel pressure is at 60psi all the time. Increasing FP gives no effect. decreasing makes things worse. Injectors are cleaned and verified not to be sticking. Scope shows almost ideal injector voltage pattern (well "ideal" according to tech guys and ScannerDanner from youtube ;)).

5. Timing

This was the last thing i thought about. I got a second hand Power FC controller and hooked it up. I "initialized" it before start, and previous owner kindly shared based map unit came with. I verified that "init" map and provided map are identical and fired up the engine. Exactly same symptoms. I then played with injector timing - and oh god, changing injector firing delay to +0.5ms smoothens out engine by a great deal. It still idles like a dead Lada, but nothing as horrible as before. That got me thinking that timing was off. Cam pulleys were aligned properly (to my understanding) - when crank is at 0 mark, cam notches must align with extrusions on timing case - they did. I pulled the valve cover to see if cams align to their internal marks - they did.

Can somebody point me in the right direction, since money's running out and im tired of replacing parts?

Thanks,

Anton

[ColinBarber]

has it ever idled correctly? Why is the air temp sensor disconnected? What intake do you have on it and where is the MAF sensor positioned?

[E910]

Have you got a picture of your MAF set up? Although if the MAF was the problem you'd have a flat stop around 4K. Is the idle low as well as rough? Have you cleaned the throttle body? There's a sensor/thermostat in front of the butterfly, when dirty effects idle.

[csr083]

Thanks for replies,

ColinBarber:

its hard to say, we rolled the car out in January, so it was cold and not noticeable. Forgot to mention that it gets better in cold. Just to be clear -its the outside temp sensor that is disconnected, not the intake one. Runs on standard manifold. Oil pressure is disconnected since it leads to the dashboard, not ECU (AFAIK, correct me if im wrong)

E910:

I never realized it had a t-stat in the TB. i got mine with plastic end that broke off, so we just removed TB heating line (by connecting steam line feed to steam line return). Can this be the cause of it? It idles bad at 800 rpm, but once outside temp goes up (to like +25C), revs drop to 600 and it vibrates really violently - even bonnet shakes. The only temporary fix is Power FC. Can you please explain me how TB heater t-stat thingy affects idle? Ill take pic of the intake during the weekend.

Many thanks.

[csr083]

Also, exhaust gas probing revealed the following:

standard ECU connected, probe shows that mixture is super lean. Once Power FC connected, results are pretty much the same. However, when injector delay is changed to +0.5ms, mixture gets to nearly stoichometric.

[csr083]

quick update.

as promised, here is the intake setup. Its some piece of ally with some noname airfilter attached to it. It works fine and idle voltage sees hardly any fluctuation. (the second bolt is not actually missing, its just not screwed in on this pic)

i also disassembled the whole intake (again!) and found that this bit was leaking a little bit of air:

with that thing being replaced and everything assembled, idle is a little bit better now, but still not really toyota smooth. It idles Okay with injector lag time being shifted (basically, injectors stay opened for longer period of time).

Also, does this timing looks okay? (white mark is at 0 = TDC)

[csr083]

I've also replaced broken TB tstat with a new one and hooked it up. no effect.

[ColinBarber]

seems a very tight bend on the intake just after the MAF sensor. Most 3rd party intakes I've seen for that engine have a greater distance before the bend. This potentially is affecting the air passing over the sensor.

[E910]

Agreed with Colin. POD filters give no end of trouble on these motors, they're very sensitive to the diameter of the pipe & placement of the MAF. I'd try get my hands on an Apexi pipe. HKS & Greddy also made them but the Apexi seemed to give the least trouble.

[AUSILVR200]

I know this is an old thread but does it idle like a rotary? check the vvti solenoid to see if it's functioning properly

[jaba0x]

any news guys?

[matto1234]

i have a 1998 altezza 275000km im running it on 91 fuel and it has a rough idle in neutral and worse in gear ,i have checked the maf ,replaced the rocker cover seals, plugs are good ,air filter not that dirty ,anything else to check?

[E910]

Why you running 91? These high compression motors require a minimum of 95 & run best on 98.

Have you cleaned the throttle body as already mentioned in this post?

[matto1234]

it runs fine on 91 ,no pinkering so i dont see why i cant continue to run it? , throttle body is clean , thanks

[matto1234]

throttle body was the problem , replaced it and it runs perfectly now

[hamzzzz]

Csr083. How did you get it fixed.?

[hamzzzz]

Old topic but im kind of in the same situation with my 3sge beams blacktop. Car runs fine on cold, idles well revs good. Etc. After the engines warmed up a bit the rpm starts going too low when not driving. The idle is low as well as rough. If i turn on ac at this time the engine stalls because rpm falls too low. Would love to hear from the original poster if and how he got a fix

[steve2006]

One of the above posts suggests the throttle body as being the cause but perhaps a fault code read would be a good idea before changing anything. With the problem being temperature sensitive it may pay to check the coolant temperature sensor feeding the ECU, if this is saying the engine is cold when it is actually fully warmed up it will overfuel and give the problems you have.

[csr083]

Old topic but i got mine fixed. Mine was a vac leak. Check your vacuum it should be someithing like 18-20 inHg, if its less than 16 it will run rough. 

The problem was that i had a leak in the brake servo, however if this engine idles rough, it shakes the manifold off the cylinder head, developing another vac leak. So i isolated the brake servo and it still ran bad, and i ruled it out thinking its not there. Then i would reseal the intake and car would run fine, but after a while the brake servo leak will make engine shake the mani off again and problem repeats. 

I would advise before swapping expensive 3sge parts do the following:

1. Get a vacuum gauge - they are cheap and super useful and hook it up to full intake vacuum. Beams idles somewhere between 600-700 rpm, so at this engine speed your vacuum should be 17-20. Note misfires will also affect vacuum.

2. Do a compression test. These engines are super awesome and compression on hot engine is spot on across the bar (dont remember exact number but do remember being impressed how even it is)

3. Are you getting good fuel pressure? Check fuel filter clogged/fuel tank sock dirty. Does your fuel pump whine more than usual? I remember reading somewhere that these engines run 60-75 psi, but from own experience can only tell that lower than 45 psi it runs like a dog.

4. Read spark plugs. Do they look lean/rich? Sorry for teaching you to suck eggs, but spark plug readings are only valid for last engine cycle. So idle your engine hot for 10 mins and then check them. Super lean plugs usually indicate no fuel pressure or vacuum leak. 

5. Also, ignition coils are not particulary strong part of the engine, but before swapping them test if they are good (there is a guide somewhere on the internet which shows how much resistance you should get across terminals).

6. make sure your engine grounds are not corroded and Battery terminals are nice and clean.

7.also check how much voltage does the alternator give out. Should be in 13-14.

 

sorry for long winded answer hope this helps.

[hamzzzz]

Guys thanks for the reply. Im trying to figure out how to check for fault codes. I have 3sge beams swapped 1973 celica and i cant seem to find the diagnostic box. Is there a way to jump or ground something directly on the ecu to make it flash the check engine light as thats been on for quite some time.

Heres some more symptoms my cars having. When its started after the engines cooled down it runs like a 3sge should. Very responsives gear downshifts fast etc. When its warm and the idle issue starts is when it starts acting slow. Its not as fast the gear shifts is very sloppy like if fully press the accelerator it downshift one at a time like 4 and 3 and then 2. And im getting a feeling it starts eating up more petrol at this time.

I will check for vacuum leaks but if there was a vacuum leak should the engine start acting funny from the start regardless of it being hot or cold?