Long Cranking Time When Warm

Hello TBricks!

I have an interesting issue I'm sorting through and would like some input on where to go next. Car is in sig.

Problem:
The engine requires lots of cranking in order to start when warm, or when it's warm outside but the engine is cold. The engine will start almost instantly in the morning. When I leave work at 4 PM the problem shows up and it happens almost every other time I start the engine. If I press the gas pedal while cranking it will start up faster but not always. Mornings have been in the 30s-40s and afternoons in 60s-70s.

The problem started after I replaced the stock injectors with white body injectors for an 850 and others. At first I thought the plugs were fouled because it took several attempts to get it started after installing these. I've replaced the plugs and O2 sensor as it was due for replacement. I also replaced the crank position sensor since it was also due. There are no vacuum leaks and the engine runs amazing once it's on.

I'm stumped. I haven't checked for codes since replacing the plugs, O2 sensor, and CPS. My thinking is that this is fuel related, in that it's not getting enough when it's warm out. The cold start injector could be supplying enough fuel on cold mornings hence the instant start up in that situation.


I welcome all suggestions that don't involve crushing it or painting the center caps gold.

Crush the center caps and paint the car gold???

I'd tend to think there's a leaking injector which floods the motor, other than the part where you say it has a hard time starting on a warm day with a cold engine. A leaking injector will often flood the intake with too much fuel to burn, and you need to cycle that through before it can run. But it eventually evaporates, which is why it starts well when cold/sitting for along time.

You could try checking the resistance on the ECU engine temp sensor. Look up some resistance/temp charts, see if it's reading remotely reasonably.

Thanks for the temp sensor suggestion. I'll check that as soon as I have a chance.

The injectors were purchased from cruzinperformance, rebuilt, cleaned, the whole nine. What are the odds I got 1 bad one?

Also, the car is already gold.

This one could be really tough to figure out. You gotta do a complete diag.

I like the theory of leaking injectors, but it really could be lots of things. You could pull the fuel rail, power up the pumps and see if they leak....

Or you could be running lean from airleaks. When a car starts cold, it really adds a lot of fuel and ignition timing and when hot, its not injecting the same amount and could be harder to start. Or the computer could be confused from the new injectors.

Long cranks can be tough to figure out. I had a dude show up in a hacked minivan with a long crank complaint that was intermittent and we told him we didn't even wanna mess with it.

CSI only kicks on at VERY cold temps. Like around freezing. Well I guess you could be around there. The way you would find out if its kicking on would be with an ampclamp to the power wire for it, or a test light or other test tool like a DSO on the negative side to monitor if its engaging.

Just kinda skimmed over this but my car had a super bad hard start when warm and it turned out to be a bad fuel pressure regulator.

Odd that your issue started as soon as you swapped injectors though.

PromiseRing said:

turned out to be a bad fuel pressure regulator.

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Was it leaking fuel into the manifold from the air hose fitting?

Funny/sad/whatever story - the first B230FT junkyard engine I got was from an unwrecked car sitting in a junkyard. On stripdown it had very, very sooty looking combustion chambers. When I put the engine back together I used the FPR that came with that engine, just sort of randomly grabbed one of the two fuel rails I had. And it immediately gushed fuel into the manifold through the manifold air line. I'm pretty sure that car hit the junkyard because of a failed FPR.

JohnMc said:

Was it leaking fuel into the manifold from the air hose fitting?

Funny/sad/whatever story - the first B230FT junkyard engine I got was from an unwrecked car sitting in a junkyard. On stripdown it had very, very sooty looking combustion chambers. When I put the engine back together I used the FPR that came with that engine, just sort of randomly grabbed one of the two fuel rails I had. And it immediately gushed fuel into the manifold through the manifold air line. I'm pretty sure that car hit the junkyard because of a failed FPR.

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It probably was leaking fuel into my manifold. Very strong fuel smell from the vacuum line. Swapped to a new one and problem instantly went away.

Great. I was worried that this was going to be involved.

There is no fuel or fuel smell coming from the FPR vacuum line, and I think I replaced it fairly recently, like in the last couple of years. I failed to mention that when I replaced the spark plugs last weekend, the plug for cylinder 1 was white, indicating a lean condition in that cylinder. The rest looked normal.

This would point to the issue being an injector (like you all have suggested)... possibly being plugged? Maybe this is why it starts up faster when I press the gas pedal down?

I won't have a chance to look at it until possibly next weekend. But as of right now all signs point to a bad injector.

n. rippe said:

But as of right now all signs point to a bad injector.

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Graph current and voltage on a two channel labscope and graph it and look for anomalies?

ZVOLV said:

Graph current and voltage on a two channel labscope and graph it and look for anomalies?

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If I knew what that meant and I had access to that type of equipment I totally would! Looks like I'll need to hit up a junkyard and pull some white injectors, swap, and see what happens.

My current bossman is smarter and less stubborn than my last and I got him to order an ampclamp that will work with our Snapon Scantool/Labscope from www.aeswave.com We got some secondary ignition pickups for $80 and an amplclamp for $100. That's within tbricker budget. They also have scopes for under $200. Technology is getting cheaper. Let's get some!

With an ampclamp, one can graph the CURRENT (AMPS!!!) a component is drawing. Fuel pump, ignition coil, FUEL INJECTOR (wink winK) If you have a fuel injector that is dead in the water, it will be completely apparent in the waveform. Voltage AND current draw.

Here is a fuel injector VOLTAGE waveform:

http://www.forums.turbobricks.com/showthread.php?t=313652



I stole this pic and rehosted it on a crap site and it just crashed my browser, and lost a nice reply too, but look at it and try to interpret. It's an ignition coil waveform:

n. rippe said:

If I knew what that meant and I had access to that type of equipment I totally would! Looks like I'll need to hit up a junkyard and pull some white injectors, swap, and see what happens.

Click to expand...

I have white injectors for cheap. 4 pintle 5 cylinder ones right, about 350cc?

Also put a noid light on cylinder one and make sure it's at least attempting to fire (getting ground pulses)

Forget noid lights. Just use a test light to injector negative.

It could be a a bad connection or dying relay. Resistance changes with temp.

If an injector is dead you won't see the tiny hump in the waveform which is the "pintle hump"! (See it in above pic at 8 milliseconds)

Cranking with the throttle wide open is the classic solution for starting a flooded engine.

Certain modern cars have a Clear Flood mode= when you floor the pedal while cranking it will kill the injectors!

I agree that it is likely a mixture issue. I wouldn't even know where to start on this one. Maybe checking fuel pressure. And doing leak down test on injectors.

It could be sooo many things. Maybe the crank sensor is getting heatsoaked, Maybe the power stage is getting hot, maybe the fuel pump relay is acting up, maybe the temp sensor is giving bunk readings, maybe the ecu is acting up. Well 02 sensor is ignored until in closed loop so it aint THAT!


What I would do is think of a high tech way of figuring it out. AFTER a solid low tech visual inspection. Secondary ignition analysis might show you if it's too rich or lean or if there is an ignition issue.

My biggest guess is the ECU is a little confused with NON stock injectors. Especially since they are larger than stock. Prob adding a little too much fuel when warm. You know what I am gonna say next.....put stock injectors back in and see what happens!

By-the-way, what year, model, and engine is this?

I think it's probably a 2.4 car...probably a 1991 744 Turbo with gold centercaps.

Car is a 1991 740 Turbo, B230FT

I have a spare injector on the way, it should get here next week. I'm only slightly pressing the pedal when warm to get it going. When it is cold, like overnight cold, it starts up immediately and it doesn't always have this issue just most of the time.

To me, 1 cylinder running lean makes me think that there is something wrong with that injector. I am getting full voltage at every connector, and the car runs really strong once it's on. Those white injectors flow more but it nothing crazy over stock. I really don't want to reinstall the old injectors but will probably do that just to rule out everything else.

Some more findings:

The engine will come right back on after turning it off and letting it sit for a few seconds. I did this 6 six times today with a warm engine and it started right up every time. This would support the leaky injector theory, yes? Also, when it does crank without starting the tach needle does not move. It's supposed to isn't it?

I haven't thanked anyone for their input yet so let me just say THANKS to everyone that has replied. Zvolv, as much as I'd love to purchase fancy equipment to diagnose this, that isn't in the budget at the moment. Thanks for taking the time to post graphs and attempt to educate me. For now, the parts cannon and guesswork will have to suffice.