Vitara 1991 brake booster replacement

[jwunsch]

Car Info:
- 1991 Vitara MT, 2 door, G16a, 4wd.
- 242000km / 150 000 miles
 - Plate in engine compartment.
  - TYPE: ETA01V
  - LAK625K17 (SWE, car has actually been sold in neighbor country FIN)
 - No AC

Hello,

Yesterday when off-roading and needing to break hard my brake-booster broke and started to leak air into the cabin right from where the break pedal connect to the booster trough firewall. Also when pressing brake's the booster is definitely working against the pedal not helping. Brakes are actually harder to press engine running compared to engine shutdown. (Tested this in minor downhill). Also pressing brakes messes up idle, ie idle RPM goes from 1200 -> 1500rpm.

As hotfix in the forest, I made a wooden plug to the vacuum tube going to the throttle-body of fuel injection thingie.

Now I would like to know where I can find original partnumber for this booster so that I can find a replacement that fits into the main brake cylinder as brakes them selves work ok and I dont want to replace both of them if I can avoid it.

Thanks in advance for any help anyone possibly offers. 

ps.

I know hot idle should be 800-1000, and I assume there is some vacuum tube leak, but I will sort it out after I get back to civilization.. its long way to part shop from here... . 1 hour drive on pavement to shop that has nothing in-store, everything must be ordered and takes shit long to get delivered. I am trusting I can drive home my about 380 mile trip.

[fixkick]

th ebooster only boosts, and when it dead. car has legit pure mechanical brakes but are harder to press the pedal only, they still have full stopping power (by design)

any air leak (aka vacuum leak) will cause too fast idle that is how all 8valve G16 EFI work, and large leak of air and vacuum brake boosters is huge leak.
the boosters on old cars like this can be hard to get.
did you ask at your local autostores first, some can, asking is base.
cracked booster diaprham...
the P/N for the booster I can tell you.
market 17 parts shows that on body tag. = Sweden LAK625K17 (for sure not santana)
suz# 51300-60a30 (or A20) there are 3 cars made then, type 1,2,3 in Europe( in USA only 1 =LHD here.)
so parts must match that.
as you may not know brakes and rules vary by country so, E17 Sweden is it. I think is type 1.
that K code means Type1. but this part is sold for RHD or LHD right and drive.(or left)
a20 = RHD (common in Europe or UK)
A30 = LHD

idle is 750 to 850 hot unless you turn on AC or other huge load accessories. 800 is normal. hot, no accessories or lighting on.
1000 is with AC on. (or other things on)varies by country this. my 91 had rear glass heater and this too 1000 rpm. ECU decides.

[jwunsch]

th ebooster only boosts, and when it dead. car has legit pure mechanical brakes but are harder to press the pedal only, they still have full stopping power (by design)

any air leak (aka vacuum leak) will cause too fast idle that is how all 8valve G16 EFI work, and large leak of air and vacuum brake boosters is huge leak.
the boosters on old cars like this can be hard to get.
did you ask at your local autostores first, some can, asking is base.
cracked booster diaprham...
the P/N for the booster I can tell you.
market 17 parts  shows that on body tag. = Sweden      LAK625K17  (for sure not santana)
suz# 51300-60a30    (or A20)  there are 3 cars made then, type 1,2,3 in Europe( in USA only 1  =LHD here.)
so parts must match that. 
as you may not know brakes and rules vary by country so, E17 Sweden is it.  I think is type 1.
that  K code means Type1.  but this part is sold for RHD or LHD right and drive.(or left)
a20 = RHD  (common in Europe  or UK)
A30 = LHD 

idle is 750  to 850 hot unless you turn on AC or other huge load accessories.  800 is normal. hot, no accessories or lighting on.
1000 is with AC on. (or other things on)varies by country this. my 91 had rear glass heater and this too 1000 rpm. ECU decides.

Hello. And thanks for the info.

Yeah I noticed that the EFI gets very confused when I press brake pedal and vacuum leaks. Engine strats vibrating and then idle goes 1400-1500. This is why I made the wooden plugs for the vacuum tube. I also could feel the leak from the actuator rod connection from pedal to booster. So the biggest leak was in the booster.

Idle went bit wonky before this trip (1200 rpm) and got back to it when plugging the vacuum. So there is some additional leak I need to fix after I get back. Plan is to change every rubber hose that connects to EFI as they are all 30 years old.

RHD countries in Europe left are only UK and Ireland. Rest of us drive LHD. So I guess my part number ends A30. So thanks for that.

[fixkick]

th ebooster only boosts, and when it dead. car has legit pure mechanical brakes but are harder to press the pedal only, they still have full stopping power (by design)

any air leak (aka vacuum leak) will cause too fast idle that is how all 8valve G16 EFI work, and large leak of air and vacuum brake boosters is huge leak.
the boosters on old cars like this can be hard to get.
did you ask at your local autostores first, some can, asking is base.
cracked booster diaprham...
the P/N for the booster I can tell you.
market 17 parts  shows that on body tag. = Sweden      LAK625K17  (for sure not santana)
suz# 51300-60a30    (or A20)  there are 3 cars made then, type 1,2,3 in Europe( in USA only 1  =LHD here.)
so parts must match that. 
as you may not know brakes and rules vary by country so, E17 Sweden is it.  I think is type 1.
that  K code means Type1.  but this part is sold for RHD or LHD right and drive.(or left)
a20 = RHD  (common in Europe  or UK)
A30 = LHD 

idle is 750  to 850 hot unless you turn on AC or other huge load accessories.  800 is normal. hot, no accessories or lighting on.
1000 is with AC on. (or other things on)varies by country this. my 91 had rear glass heater and this too 1000 rpm. ECU decides.

Hello. And thanks for the info.

Yeah I noticed that the EFI gets very confused when I press brake pedal and vacuum leaks. Engine strats vibrating and then idle goes 1400-1500. This is why I made the wooden plugs for the vacuum tube. I also could feel the leak from the actuator rod connection from pedal to booster. So the biggest leak was in the booster.

Idle went bit wonky before this trip (1200 rpm) and got back to it when plugging the vacuum. So there is some additional leak I need to fix after I get back. Plan is to change every rubber hose that connects to EFI as they are all 30 years old.

RHD countries in Europe left are only UK and Ireland. Rest of us drive LHD. So I guess my part number ends A30. So thanks for that.

hot too high idle,  causes, are many.  (vacuum leaks yes ) your is now defeated that one leak to booster huge hose is blocked.
besides hoses, bad an
themostat bad or missing and stuck wide open.  coolant way too cool.
is the CEL lamp (SES) glowing key one, then stays out , running,  if no out,  that is limphome mode and there are no idle controls in LIMP , is this is #1 simple check.
ISC dead (and is in LIMP) but if the valve is stuck open (CEL lamp off) then that too  is a cause.
IAC, in bast of TB (throttlebody) stuck open or the hot water hose is clogged to it.  IAC closes at 65C !  normal 82C is hot engine
all those vacuum hoses new,  the objects on the end of any hose can leak air and fail. (pinching hoses is good test to prove that) or vacuum hand pump and leak down tests work great too.

TV stuck open, if there is gun under the TV throttle valve butterfly plate,  that too causes too fast idle
as will any of the 3 throttle cables not with free play per FSM boot , TV cable is 10mm free play.(loose it is , and spec)


that is about it. for 1500rpm,  this is hard fail that. on hot engine. cold is normal, iAC runs 1500rpm cold.

[fixkick]

also, air leaks do not cause vibration, just like using, right foot for 1500RPM , causes no abnormal vibs.
vibration means misfire.
sounds like limp mode to me, or bad spark plugs or wires. use MAG wire on this car, not carbon core or nasty silicon core, mag gives you lots of good spark levels.
spark plugs need to be at gapped at .028" spec. 0.7mm

vacuum leaks are discovered by the MAP sensor and it with ECU sets fuel mix perfectly for any vacuum leaks, on this car, very unlike the 16V car with MAF.
This perfectly means no misfire. with vacuum leaks so tell me there 2 problems, but most cars this old are RIFE with problems. so .. nothing new there.
not with standing bad vacuum hose to MAP , bingo huge vibrations, and bad fuel mix. super rich mix , so this hose is first. (for a clean burning engine)

good luck to you !!!!

[jwunsch]

CEL light ok on power-on engine stopped. All lights go away on startup. I read error codes at spring just ok (code was if I remember ok 13 - bad O2 sensor).

I have recently changed (related to points you said):
- spark plugs, RAD, fan clutch, STAT (190F), O2 sensor

Engine runs very stably without vibration unless I remove the plug from booster's vacuum hose. When I do that, it vibrates a bit until it ups RPM to 1400-1500 no vibration then. When I put the plug back it drops to 1200rpm, no vibration.

My fuel usage was on fast paved road travel about 8,3l / 100km (around 28mpg) and when driving only 80-90km/h (50-55 mph) it was around 7,5l/100km (31mpg). So I am guessing spark is ok, so is lambda and not in limp mode. Also it feels that all power is present. I did drive 130+kmh (80mph+) on motorway so definitely all power is present as its about the suzuki spec topspeed.

I think my ISC is busted, but before clutch replacement hot idle was 800RPM and when putting lots of electrics on it went down 600 RPM. But this high idle of 1200 RPM started after clutch replacement and some welding done on back of the frame (they had to drop tank).

So my best guess is that when tilting engine and doing other stuff some very bad rubber hose broke a bit.


One thing I have noticed. WHen engine is hot (STAT open) and I press lightly throttle, RPM goes slowly upto 2500 and then drops to 2300 and then it does that 2300->2500->2300... for ever until I press more throttle. Some strange cutoff error there. I guess the EFI changes mode there and gets confused.

So anyhow I think I will first just change all the hoses as they are anyways going to break very soon. Then if the problem persist, check other things.


I fear that some previous owner has done a lot of nasty things there. There are DIY electric fixes here and there, like they had at somepoint bypassed the fuel pump relay and then switched back to the relay. ALso could be that somebody has tampered with the EFI "do not touch nut".. as the HOT side knob for tuning something (that has AISIN brand text there) is broken off. Cold side knob exists.

So the car is bit of a mystery.

[fixkick]

CEL light ok on power-on engine stopped. All lights go away on startup. I read error codes at spring just ok (code was if I remember ok 13 - bad O2 sensor).

I have recently changed (related to points you said):
- spark plugs, RAD, fan clutch, STAT (190F), O2 sensor

Engine runs very stably without vibration unless I remove the plug from booster's vacuum hose. When I do that, it vibrates a bit until it ups RPM to 1400-1500 no vibration then. When I put the plug back it drops to 1200rpm, no vibration.

My fuel usage was on fast paved road travel about 8,3l / 100km (around 28mpg) and when driving only 80-90km/h (50-55 mph) it was around 7,5l/100km (31mpg). So I am guessing spark is ok, so is lambda and not in limp mode. Also it feels that all power is present. I did drive 130+kmh (80mph+) on motorway so definitely all power is present as its about the suzuki spec topspeed.

I think my ISC is busted, but before clutch replacement hot idle was 800RPM and when putting lots of electrics on it went down 600 RPM. But this high idle of 1200 RPM started after clutch replacement and some welding done on back of the frame (they had to drop tank).

So my best guess is that when tilting engine and doing other stuff some very bad rubber hose broke a bit.


One thing I have noticed. WHen engine is hot (STAT open) and I press lightly throttle, RPM goes slowly upto 2500 and then drops to 2300 and then it does that 2300->2500->2300... for ever until I press more throttle. Some strange cutoff error there. I guess the EFI changes mode there and gets confused.

So anyhow I think I will first just change all the hoses as they are anyways going to break very soon. Then if the problem persist, check other things.


I fear that some previous owner has done a lot of nasty things there. There are DIY electric fixes here and there, like they had at somepoint bypassed the fuel pump relay and then switched back to the relay. ALso could be that somebody has tampered with the EFI "do not touch nut".. as the HOT side knob for tuning something (that has AISIN brand text there) is broken off. Cold side knob exists.

So the car is bit of a mystery.

thank you for the update.

so this ISC looks like this.  our TB is made by Mukni.



the ISC is here, note the ECU side plug not seen on 89/90 years here. (early year is 2 pig tails wires)
the 5mm Allen wrench hex screw , also a never touch screw but when very old we do adjust it as inside is rubber seat that gets worn and leaks.
when that Happens I set the screw so the piston inside just touches the, seat gently.
the 4th screw, (is air bleed screw the correct name is Duty cycles setting , and is set to the the IAC is at 50% duty at hot 800 rpm.

91 USA version.  91-95 in USA TBI (aka. SPI, single point injection)





Does your ISC look just  like this?

see stamp Mukuni on IAC housing?  note the white painted never touch screw, some are plastic capped over. that is the factory .0005" TV gap/bore setting. only.

The DP  screw is for setting  only the dashpot idle speed,. hot. started to 2500 rpm. (active only at first start of engine for 3 to 15seconds DP actions only)







there are ways to block hidden air paths the IAC to see if it leaks hot. IAC is thermal only cold idle.


 or simply us pan of hot water to be sure it closes as I did here.  I did this with drill bit  shanks, as feeler gauges.

before doing all this, above, we make sure all hoses vacuum do not leak end to end.

also you stated one more problem above.
"RPM goes slowly upto 2500 and then drops to 2300 and then it does that 2300->2500->2300.."
this wrong, and I know that cause. (assume booster hose plugged and no other vacuum hose cracked wide open and changing illegal air flows via normal vibration)

this is the TPS idle switch set wrong. the ISC must go off line with right foot pressed, on your car it is set wrong, and the ISC is wrongly active fighting the right foot actions. 


The idle switch is set. to. .016" (0.4mm) (throttle cable free play must not be zero, 10mm is spec  on able)
the no touch screw rear lower must not be wrong or molested.  0.0005' gap in TV bore.
then we set the air gap on that screw with .016" feeler gauge.
then set the TPS idle pins to go to open circuit at .016"

step1 https://fixkick.com/TPS/TPS-p91.JPG

step2  https://fixkick.com/TPS/TPS-p92.jpg

step3 https://fixkick.com/TPS/TPS-p93.JPG



links to my TBI slide show are here.

[fixkick]

as you move the throttle pedal, even the most SLIGHTLY the TPS idle pins open and go to 5vdc.
yours opens way to late. so is set wrong
the ISC is fighting your right foot.

[fixkick]

the TV bore gap size is and was never ever, told by SUZUKI.
I use my most small feeler to do that. .0005" (jag told .001")
here is a very rare book view on rare car that does shows this sitting,  set it once and never touched again.

JAG: example.  some folks love to mess up this screw.  engine in LIMP mode, idles too slow and black smoke out tail pipe, they panic and set this.
if we must panic, use the bleed screw not this one. (on hot engine ISC controls idle speed,  IAC cold.)

[fixkick]

idle and vacuum must be controlled and adjusted in the correct order. (repairs first then calibration)
healthy engine ,compression good, thermostat ok, spark timing set to spec. then below list.

1.  no vacuum hoses leak  or the TB base gasket, no things on end of hoses leaking air, "devices"   If 3speeD A/T the modulator hose end not leaking too.
   
2. TV gap set to 0.0005 to .0001" inch.
   
3. TPS idle switch set to .016" trip point.
   
4. IAC CLOSED AT 150F UP.
   
5. ISC NOT JAMMED UP, OR leaking grossly with damaged seat as many have now this old.
   
6. ISC duty cycle set to 50% by turning the air bleed screw front center of TB.
   
   

on this car and this ECU any gross air leaks may cause the ECU to go nuts.  it may even use the ISC to hunt idle RPM wildly. (trying hard to gain control and fails)