Cold starting and poor initial idle issue

[octanejunkie]

In order to start my '99 I have to give it gas immediately after starting or it will die. 1 out of 10 times pumping the gas BEFORE cranking seems to help.

After starting, I need to hold the RPM around 1,500-2,000 for about a minute, at which point if I rev it over 3,500 rpm and let go of the gas it will hold a 1,600 RPM idle and run normally on its own; eventually settling down to around 850-900 RPM once warm.

Different problem with warm starts, sometimes it's fine, but sometimes it idles rough and low until I flash the RPM past 3,500 RPM.

I just cleaned the throttle body with no improvement. Any ideas?

 

[thegipper]

I would check the fuel pressure at the rails. To me, it sounds like a fuel issue. You could try cleaning the MAF also.

Could be faulty fuel pump, clogged filter, injector(s). Do you have and CEL on?

I would start there and see if its any of those issues.

 

[AntleredRuin]

Do you have any issue with stalling while driving?
My FPR gave out a year ago and I had the same starting issue as you. Once it warmed up it stayed steady.

However, when floored (or even just harder acceleration) it would stall out. Pop it in neutral, and it would start right back up again. Made merging onto the freeway downright scary.

 

[octanejunkie]

I would check the fuel pressure at the rails. To me, it sounds like a fuel issue. You could try cleaning the MAF also.

Could be faulty fuel pump, clogged filter, injector(s). Do you have and CEL on?

I would start there and see if its any of those issues.

No CEL, fuel filter is within a year old.

I have not checked fuel pressure at the rails, according to my "mechanic" it wasn't easy for him to do; but I've not tried myself. I do add a 1/2 bottle of Seafoam to a tankful once every few months - but no, I can't say it's not fuel related.

 

[octanejunkie]

Do you have any issue with stalling while driving?
My FPR gave out a year ago and I had the same starting issue as you. Once it warmed up it stayed steady.

However, when floored (or even just harder acceleration) it would stall out. Pop it in neutral, and it would start right back up again. Made merging onto the freeway downright scary.

No stalling, symptoms exactly as per my OP, hard to start when cold and after about a minute I can flash the RPM to 3,500+ and it will idle on it's own. When I'm driving I can accelerate no problem, lot's of power, no delays or bogging.

 

[LittleCaesar]

Your mechanic, if he has one, needs to tear up his ASE cert card.

Here is how the fuel pressure needs to be checked at the rail:
https://www.youtube.com/watch?v=JiA5v9u97OQ&feature=youtu.be

 

[desertegal7]

Catalytic Converter

You may try to check that your catalytic converter is not being partially clogged

 

[gamefreakgc]

No one has mentioned the IAC valve under the throttle body yet. Often the culprit for idle issues, since it controls the amount of air going into the engine at idle (read: if clogged it dies).

 

[runnyrunnerton]

Just answered a coolant leak question with this. Before i changed motors, i smelled sweet smell from exhaust and my startup was sputtering. Usually this is a fuel issue, but the Idle Air Control Valve gasket may be going bad and allowing coolant in the intake. Its a $4.00 gasket and might be just the ticket, was for me. New motor, same smell still slightly hesitant on startup, new gasket, no more sweet smell and she pops to life right away.

 

[19963.4lsr5]

During warm up from cold the engine is in inrichment mode and running air fuel ratios as low as 8 to 1. During that time it requires a lot more fuel flow than normal after warmup is complete and the AF settles in at 14.7 to 1. During that warmup you fuel system may not be able to keep up with the extra demand.

When did you start adding seafoam to the tank? Before or after the filter change? You know where I'm going with this question.....


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[lbhsbz]

Classic idle speed control valve sticking/failing. Don't bother trying to clean it. The aftermarket ebay units work fine. Just change it.

 

[97t4r81]

Could also be the check valve in the fuel pump. I had issue of hard start,pump pedal and several cranks later would start and idle normal. I'm dumb so I just replaced pump as I couldn't find a tester and lost patience. Test fo pressure . Hope ya solve

 

[lbhsbz]

Could also be the check valve in the fuel pump. I had issue of hard start,pump pedal and several cranks later would start and idle normal. I'm dumb so I just replaced pump as I couldn't find a tester and lost patience. Test fo pressure . Hope ya solve

pumping the pedal does nothing on a fuel injected car...there's no accelerator pump.

losing residual fuel pressure would cause a long crank, but have nothing to do with a poor idle after it started. A couple key cycles to restore system pressure before cranking will make it start and run like normal if the check valve is leaking down.

This will not cause the symptoms the OP is having.

 

[97t4r81]

pumping the pedal does nothing on a fuel injected car...there's no accelerator pump.

losing residual fuel pressure would cause a long crank, but have nothing to do with a poor idle after it started. A couple key cycles to restore system pressure before cranking will make it start and run like normal if the check valve is leaking down.

This will not cause the symptoms the OP is having.

It could be multiple issues, one could be the check valve, another poster said as well. Only offering friendly advice that helped me.

 

[lbhsbz]

I was simply clarifying so as not to send the OP down a road that wouldn't fix it. Having an understanding of how the systems work is critical determining why they don't.

No offense intended

 

[JRZEE2000TR4LTD]

I'm having Deja Vu. I thought this was your other thread where I suggested the IAC valve and I'm going to suggest it for this one too.

 

[octanejunkie]

I'm having Deja Vu. I thought this was your other thread where I suggested the IAC valve and I'm going to suggest it for this one too.

I know you did and thank you, it's like deja vu all over again *winks*

I'm out of town till after the new year but I will pull and test the IAC, and swap the gasket while I'm at it.

Would it be safe to partially submerge the IAC in carb cleaner over night (obviously not submerging the electric motor) assuming it tests ok?

 

[octanejunkie]

You may try to check that your catalytic converter is not being partially clogged

The cat was almost stollen 2 years ago (they tried cutting it off parked overnight on the street) and my muffler guy checked it when welding it back in - it was fine then...

During warm up from cold the engine is in inrichment mode and running air fuel ratios as low as 8 to 1. During that time it requires a lot more fuel flow than normal after warmup is complete and the AF settles in at 14.7 to 1. During that warmup you fuel system may not be able to keep up with the extra demand.

When did you start adding seafoam to the tank? Before or after the filter change? You know where I'm going with this question.....

I use SeaFoam in all my vehicles ONCE in a while, both before and after the filter change in this car. However I don't think it's a fuel system issue - I have ZERO other fuel issues while driving.

Classic idle speed control valve sticking/failing. Don't bother trying to clean it. The aftermarket ebay units work fine. Just change it.

Like these? Do you have a specific link to share? Thanks!

Could also be the check valve in the fuel pump. I had issue of hard start,pump pedal and several cranks later would start and idle normal. I'm dumb so I just replaced pump as I couldn't find a tester and lost patience. Test fo pressure . Hope ya solve

I guess I need to either invest in the fitting/gauge or find another mechanic that can do it for the piece of mind.

I was simply clarifying so as not to send the OP down a road that wouldn't fix it. Having an understanding of how the systems work is critical determining why they don't.

No offense intended

I appreciate all the input and advice from those more experienced than I.

Like my OP says, one in 100 times fully depressing the gas pedal before starting seems to make a difference, meaning the car starts and goes into startup enrichment mode all on it's own. The other 99 times I have to manually do it with my foot, and after about a minute holding at 1500-2000 RPM I can flash it to 3500+ and it will then pickup and idle on it's own (in the 1500-2000 RPM range, then settle down once warmed up)

 

[19963.4lsr5]

I'm pretty sure the Toyota IAC is not stepper motor based but a coil. I may be wrong....but with engine warmed up and idling spray carb cleaner through the IAC's bypass hole a bunch of times and see if the idle picks up. The engine will want to stall when you spray. Just give short squirts and let it recover


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[97t4r81]

I was simply clarifying so as not to send the OP down a road that wouldn't fix it. Having an understanding of how the systems work is critical determining why they don't.

No offense intended

All is well. Kindness is alive.