RPM drop and stall on load at idle

[Xulfiqar]

Good going

Do voltage drop tests on both sides of the starting circuit, it maybe a bad ground connection. Or even a bad positive too which is failing with heat.

Been there done that, banged head on wall (wall dented) and learned a lesson. It was a stupid BMW E36 in Pakistan with ustadified “earth wali taar”

[thatdevsherry]

Will do. Wanted to do it some time ago but forgot about it until now. Will test when I get a second pair of hands (aka cousin).

I also remember something that maybe is normal or not. Perhaps you could comment on this.

Some time ago I was diagnosing if power steering pump is putting too much load. I had disconnected the PSP switch and started turning the steering wheel lock to lock. The RPMs dipped a lot before recovering but occasionally the engine stalled. FSM says that momentary drop will be more when disconnected, but doesn't mention stalling on full-lock if PSP switch is not connected.

PSP switch helps with load but even when it's not connected, I assume it shouldn't let the engine stall, just that rpm should drop quite low before recovering.

Also the way I'm able to stall the car involves pumping the brake to bring rpm down a lot, and then the steering input is what kills it. Pumping the brakes alone doesn't cause stalling. Maybe brake booster and power steering both or one of them is the issue?

Don't really know any way to test power steering pump at home w/o a gauge or something. Funny that my cousin's baleno's PSP is in really bad condition (groans on slightest steering, spits out fluid on redline etc) but doesn't exhibit this behaviour.

Pending:
- vacuum gauge test
- starter circuit voltage drop test

EDIT: Probably should repeat this test now that I've adjusted base idle. Maybe it's good now. Although engine didn't stall as I mentioned in last post, I did try doing the same test by being near full lock, brake pump and hold until rpms dropped to lowest (550) and then slight steer to full-lock. Engine stalled.

EDIT 2: Since I can log engine params now, will try repeating the different tests and see if something pops up.

Looking at last 2 drive data (one before and other after base idle adjustment). The lowest rpm drop when braking and steering was 600, whereas before adjustment one time it dropped to 500. Below is after adjustment snippet.

[mohd.razaan]

Been following for a while, I had the same issue and did narrow it down to power steering and brake switch. Check out my post you will be pleasantly surprised how identical these issues are.

Do u by any chance have the auto-lock doors thing connected to your brakes?
Also check your alternator before changing battery.

In my case there was a bad ground from alternator and a shortsomewhere in the harness due to oil leakage. I figured it out after a year because the dash trim lights went out and kept blowing fuses

[thatdevsherry]

I haven't been able to find the specific post you mentioned to see how similar they are.

Yeah auto-lock with brake was present when i bought the car. Didn't really give issue before rebuild. Although one thing did annoy me that whenever the brake lights come on, the dash lights dim a bit, and so does the interior light. The auto-lock seems to be functioning right. Only activates when doors are unlocked and i press brake after a few seconds.

I had tried doing the brake + steer test with brake light fuse removed to remove brake light influence but still stalled.

Similar is whenever doors open the flasher relay closes it brings rpm down a bit. Even turning on hazard lights dims the dash lights, just less than the flasher relay.

I remember checking the alternator (alternator output, voltage drop from alt-batt) and it looked good. I think i haven't logged it in this topic so will check again (prolly at the same time when I'll test starter circuit).

Thing is, these issues existed before rebuild and the stall issue (and slow crank) appeared as soon as I took the car back after rebuild, which is why I'm super focused in the engine bay area and not cabin wiring etc.

I'll IA update soon about the alternator and starter circuit tests so we can check them off from the list.

[Xulfiqar]

Do voltage drop test on the ground side on the main cable, and put a grounding strap on the alternator bracket too. Its usually missing

[pwuser161684645588]

AssalamoAlaikum bhai, i also have 1300cc baleno. Could you please explain to me how you do the butterfly adjustment?? or if you could send me a video or YT link. Since your way of setting would exactly work with mine so i prefer you explain all the points. I want to set it myself.
Thank you!

[mohd.razaan]

I think I have lost that account from which I had originally posted. But I still have the screen recording of the obd2 scanner that showed various readings right before it stalls.
Let me know if u want it or how can I post it here.

It stalled exactly like you described: brake+ hard steering.

Then one day a mice entered my car and chewed on the auto lock kit wiring and I never stalled again. But please, before u go deeper in the engine just disconnect power steering and auto brake kit or just auto brake kit. I am almost 99% sure thats the culprit.

I know you checked by disconnecting the brake fuse and it makes no sense lol. Its more for me and the unsolved mystery that made me sold my car due to this exact issue. Let me know if u do try it... hooked to your thread

[thatdevsherry]

An old video showing me trying the brake and steer stall.

My procedure of pumping the brake and steering isn't very realistic so the original way I found out was

1. press brake
2. release brake
3. as rpm starts going up a tiny bit after release, start steering from straight ahead position
4. as i steer, rpm starts dropping and engine stalls.

This is not near full lock so psp switch has not activated yet. Shared because on warm engine I did this today again and engine stalled.

Other tests I'll try tomorrow IA and also see the param logs while doing this. Need to carry around a laptop currently so I can't do it anytime I like xD

[thatdevsherry]

I'll see if I can make a video of it because I'm not good at explaining in text. But the process is as follows (need a scanner for this):

1. connect scanner when engine is running and warmed up
2. on scanner, there is a button for "actuation tests" or something similar
3. in it, select "iacv actuation" or anything having "iacv/iac/isc".
4. scanners usually check that engine is warm, not moving and rpm is under 2k I believe
5. once it starts, it usually will start with the lowest value. If a mechanic hasn't misadjusted your butterfly too much, you will notice the engine slow down
6. see the "engine speed, isc duty cycle, and desired idle" params
7. desired idle might be 192 or something, just make sure it's the lowest (select "sub" or whatever button the scanner has to send a lower value, but it might already be lowest)
8. check that isc duty cycle is 1%
9. check engine rpm, it should be near 650

if rpm > 750, start closing butterfly until you get near 650, isc duty cycle should already be 1% due to the badly opened butterfly

if rpm < 600, start opening butterfly until you get to 650, isc duty cycle will be more than 1% until you get near 650. then check isc duty cycle.

if duty cycle is still more than 1% (happened when I was adjusting another baleno), kinda fiddle with stop screw (bring it back down or up or something) until ecu stops being stupid and closes it to 1%

goal being, you should have the following end result when in the actuation test:

• engine speed should be around 650
• desired idle is set to lowest value (192, 500 or something. you'll know because the "SUB" button will be gray
• isc duty cycle is 1%

[thatdevsherry]

Can I borrow the mouse? Seems like a good technician xD

I attached a video showing the same, however this method has the brake being pressed and released before steering. Pretty sure auto lock would not interfere.

@Xulfiqar sorry for spam, but is it normal for psp switch to start activating a bit late as engine warms up?

On cold engine, slight steering from center activates psp. As engine warms up it starts moving closer to full-lock.

Come to think of it, the obnoxious psp switch that I installed before still activated close to center when warm iirc. maybe this switch is having an electrical issue as it heats up rather than the psp fluid getting thin when warm. Although I stalled once even when I had that switch. So that's a fact to consider.

I think I'm going all over the place. I'll come back after testing alt (no ground strap on it last i saw) and starter.

EDIT: I also remember sometimes at idle when ac was on and it turns off, the rpms dipped down a lot. Same when radiator fan turned on the rpm would drop quite a lot. Feels like iacv issue but I cleaned and did replace it. Duty cycle goes up slowly maybe. I mean when rpms drop I can hear the engine going clunky clunky and then recover after 5 seconds.

Even when i once turned into a street and rpm dropped I let off everything with clutch pressed and the rpms just kept near 550. ISC takes a long time to realize and recover..

[thatdevsherry]

So uh I was doing voltage drop tests on starter circuit and the values went really really low, around 6V.

Crank became slowww. Car wouldn't start then. I had to jump start it myself by pushing alone.

But uh, once I stopped the car, it would not start after that. Crank was super slow.

I thought battery is toast, I replaced battery with a "new" one (spare me pls I got flooded smol one not sure how long it lasts).

But car still didn't start. Turns out starter had seized up (black contact marks on inside of that thing (not sure of its anatomy).

Electrician cleaned and greased it up. Works fine now. Crank is super fast. I didn't swap back old battery since the load tester showed it was near red area.

Will record doing brake and steer logs when I find time. Wasted today doing it on seized starter which was giving false reading due to excessive resistance.

[Xulfiqar]

You had 6v on a drop tesr? Or 6v on battery poles?

Both are two different things.

[thatdevsherry]

Another update (sort of good)

Got back home. Was testing stall and I turned steering 90deg from center and psp switch turned on. Before it was close to full lock at warm engine. Now at warm engine the ON location of switch did not change (same as cold).

Tested with brake press and release and then steer, rpm went down a bit (expected) but psp switch turned on immediately and rpm went up a bit (not too much like the old psp switch used to do, which is weird because it's a simple binary switch).

I'll investigate this further to see if it has indeed improved.

EDIT: gist of this post being that after changing battery and repairing starter, psp switch started to respond close to center. And not too obnoxiously. Maybe battery helped stabilise electrical stuff or whatnot. Pending confirmation.

[Xulfiqar]

What oil is in the power steering? The psp works on pressure, cold oil being viscous will trigger it, you are supposed to use a 20wt hydraulic oil in it, cheapest of which is regular dexron3 atf

[thatdevsherry]

My bad I wrote quickly.

It was between starter + and solenoid case (which i realized is wrong and I should gnd to starter motor case.

Battery voltage drop was around 8v at that time with slow cranks.

I'll test voltage drop again on starter, battery and b/w starter + and batt + again just to see if it is good or not since starter now runs at speed of light.

Alternator was putting out 14.5V at idle (alt + and alt case). Battery running was 14.41V (didn't check voltage drop b/w alt and batt).

[thatdevsherry]

Ah yeah FSM mentions using equivalent of dexron 2 or 3. I am pretty sure I'm using some generic one that I didn't read (pls spare me).

I'll buy dexron3 atf and flush the system out (got some small turkey baster type things for kid and it's 500ml) to eventually flush it out with dexron3.

Or maybe I can remove one of the pipes going to reservoir and steer out all and add new, that seems way easier.

[Xulfiqar]

Battery voltage drop is done like this

Negative of battery to negative of starter body with dmm set to dcv 20v

Any voltage here means you have a loss, e.g. if you measure 3v it means you lost 3v in the negative cable (its bad)

Similarly you check positive at battery positive to starter main cable lug, same thing here, test for voltage drop with dmm set to dcv 20v

Disconnect the crank sensor to do a reliable test of the starter load.

What you are doing is basic batterry voltage test, which is pretty useless unless you have a graphing dmm or a very fast one.

[Xulfiqar]

Disconnect return line at reservoir and put that to drain into an empty container (old oil bottle)

Plug the return barb on the reservoir so oil doesnt pour out as you add,

Fill up the reservoir, lift the car up so wheels are in air, unlock steering, do not start engine, spin the steering slowly to pump oil out, keep adding fresh oil and keep turning the wheel lock to lock (make sure reservoir never empties)

After a full 800 ml is in, remove the makeshift plug on the return barb and connect the cars return line to the reservoir, top up the rest 200 ml to between hot and cold mark.

Job done.

[thatdevsherry]

Will do.

I did do voltage drop test like you mentiioned on positive and negative side but I'll redo after starter repair and also because I was alone so was a bit hard to crank and also place leads.

before stareer repair, starter lug to batt + pole was 0.78V and solenoid case to batt - was 0.96V. Both are high. But will reconfirm after repair (this time starter case to batt -).

Had taken out fuel pump relay to prevent car from starting while I was doing the test.

I'll report back soon IA.

[pwuser161684645588]

AssalamuAlaikum brother. I also have a similar kind of issue with my Baleno. When the engine is cold, the startup is very quick—almost like a half self-start. However, as the engine gets hotter, the starter cranks for longer, and in some cases, I have to crank it twice. A mechanic suggested replacing the starter bushes, so I did. After that, the cold starts became even quicker, but once the engine warmed up—especially after a 20–30 km drive—the cranking time increased again. The mechanic then suggested removing the starter to check the connection between the starter and the flywheel, as it might be faulty. What would you suggest??