Help! Cold start problem

[miverson1]

89 Coupe. When starting cold, I have to open the throttle to keep the engine running. After warm-up, about 140, runs fine, but does have some hesitation and some sluggish accel. Have checked the EGR, Fuel Pressure 39. replaced the Fuel Filter and metered out the injectors, 16.4+- .1. Car sat idle for about 1 year. Thought maybe fuel was bad. Drained tank and refilled with fresh fuel. Added Techron, fuel injectors dirty?, but still no good. Six of the injectors are OEM with two appearing to be after market, Black Body. Could the injectors be leaking through? Have pulled the plugs and found some fuel residue but not a lot. Also did a complete tune up, plugs, rotor etc, and I did replace the EGR. Also no vacumm leaks. ??

 

[Schrade]

89 Coupe. When starting cold, I have to open the throttle to keep the engine running. After warm-up, about 140, runs fine, but does have some hesitation and some sluggish accel. Have checked the EGR, Fuel Pressure 39. replaced the Fuel Filter and metered out the injectors, 16.4+- .1. Car sat idle for about 1 year. Thought maybe fuel was bad. Drained tank and refilled with fresh fuel. Added Techron, fuel injectors dirty?, but still no good. Six of the injectors are OEM with two appearing to be after market, Black Body. Could the injectors be leaking through? Have pulled the plugs and found some fuel residue but not a lot. Also did a complete tune up, plugs, rotor etc, and I did replace the EGR. Also no vacumm leaks. ??

Notice VERY closely the exhaust at startup. What color?

 

[miverson1]

Notice VERY closely the exhaust at startup. What color?

Should have mentioned this, exhaust is clear, no white or black smoke, but there is a distinct Fuel smell when it is running rough. Also failed to mention that all the injectors appear to be firing, audible clicks, and that when warmed up the pulses to the injectors all appear the same using a scope..

 

[miverson1]

Found my problem. The ECM controlled solenoid for the EECS was bad. Did not close with ECM signal. And the outlet hose to the purge canister from the solenoid was cracked. Always had a vacuum leak through the bad solenoid and the bad hose. Hard start when cold, and hesitation and sluggish accel when warm.

 

[Schrade]

If the hose to the EVAP cannister was leaking, then you had occasional SES (DTC32 EGR), probably stored as history ALWAYS... Light would light up at highway speed huh?

 

[Dark90]

My 1990 is having a similar problem. It doesn't actually die when its running like garbage, but it sure as hell wants to. Idle RPMs drop to about 400-500. After it gets up to operating temperature my problems dissappear, but occasionally come back when sitting at a stop light. I also get nice dark puffs of black smoke out of my exhaust while this is all going on. Occasional Code 32 at highway speeds. Turning the car off for a few seconds and then back on makes the SES light go away for a few minutes.

My FSM hasnt arrived yet and I gave up on my Haynes manual. What is the EECS and where is it located? This is the last issue I need to address before I begin my engine buildup. :dancenaughty

 

[Schrade]

My 1990 is having a similar problem. It doesn't actually die when its running like garbage, but it sure as hell wants to. Idle RPMs drop to about 400-500. After it gets up to operating temperature my problems dissappear, but occasionally come back when sitting at a stop light. I also get nice dark puffs of black smoke out of my exhaust while this is all going on. Occasional Code 32 at highway speeds. Turning the car off for a few seconds and then back on makes the SES light go away for a few minutes.

My FSM hasnt arrived yet and I gave up on my Haynes manual. What is the EECS and where is it located? This is the last issue I need to address before I begin my engine buildup. :dancenaughty

Welcome to the boards!

You have at least one vacuum leak, and another in vac hose that supplies vacuum to EVAP cannister.

This is a SPECIAL vacuum leak. Standard vac leak test does not apply, since EVAP purge vacuum is applied ONLY when the ECM tells the EGR solenoid to purge the EGR AND the EVAP.

First, READ (don't DO it yet) this standard vac leak test, and make sure you understand it.

ME

No one got the proper technique for vacuum leak detection... :confused

FIRST; block the pedal, or block the throttle linkage. YOU HAVE TO DO THIS TO GET A STEADY IDLE , around 1,250 rpms, or a little higher. If you don't, you can fish a propane hose, or WD40, or Krylon, or hair spray, or pee, anything, until you need a sweater in Hades, but if the motor is lopin' already from a vacuum leak, you ain't gonna' find any vacuum leak, unless it's so big that Little Jack Horner can stick his thumb in it and pull out a pineapple NOPE.

AFTER you get a steady idle, THEN, you can spray starting fluid everywhere - that's the best detector, because it's vapor pressure is very high - a LITTLE at a time, until you get the SURGE. Follow the vacuum lines to the EVAP cannister too (with mods below). You might even have to follow the EVAP lines from the EVAP cannister to the gas tank too, but that vac leak will show up as a DTC 32 EGR fault, and won't normally show as loping idle, unless the EVAP cannister has been by-passed (been there, saw that uh-huh).

If you get a surge in a tight spot, and can't tell exactly where it is, light a book of matches, blow out the match heads while they're still burnin', and feed the smoke to the tight spot.

Fear not the starting fluid; you cannot put the can down fast enough and light the matches fast enough to catch the starting fluid, because the vapor pressure is so high.

Bookmark this post YUP.

Wrench Wizard OUT!

If the hole in the EVAP vacuum hose is not big enough to see, you'll have to modify the vac leak test, since vacuum is NOT continuous to the EVAP.

To modify the test for the EVAP vac circuit, pull the hose that goes to the EVAP cannister FROM the intake. Pull it where it feeds INTO the intake, and connect it to a CONTINUOUS vacuum source (remember, the normal port is NOT continuous, rather it is open ONLY at speed when the ECM open the EGR solenoid).

Once you have it 'T'ed into a CONTINUOUS vacuum source (there's several CONTINUOUS ports, some on the throttle body, some on the intake - just make sure it's 'T'ed in tightly), THEN do the leak test described above.

You WILL have to feed the starter spray everywhere, as described, and ESPECIALLY along the modded vac line FROM THE MODDED 'T', TO THE EVAP CANNISTER, SINCE THAT'S WHERE AT LEAST ONE LEAK IS.

If you can get it right, you're the man. I know only one other guy who did the REGULAR test right, and found his leak...

EDIT:
THIS IS ANOTHER POST TO BOOKMARK YUP!

 

[Schrade]

I got a vacuum leak - arghhhhh!

You know where you can take your bookmark posts...

Today my trusty little Nissan lit me up SES DTC po455 VACUUM LEAK (LARGE) IN EVAP SYSTEM.

While reading my EVAP diagnostics (for Nissan), I learned the RIGHT way to test EVAP purge vacuum circuit, instead of the moddified vacuum test as described above (which WILL work, BTW... )

Since the EVAP purge does not have CONTINUOUS vacuum, then instead of swapping hoses to make it CONTINUOUS (and expose the leak), apply 12V to the EVAP purge solenoid, which open the vacuum to the EVAP vacuum system. BRILLIANT!!! Now we know why Schrade ain't a pro wrench!!! (see sigline)

But with TPI/L98, the EVAP purges through the EGR port, so, do we apply 12V to the EGR solenoid, to supply vacuum to the EVAP circuit, and expose the vac leak??? Or is there a EVAP purge solenoid as there is on LT1???

Anybody???

 

[Schrade]

I don't have my TPI anymore - and no one will chime in with pics or info, so here's how it will work, although on a slightly different vehicle.

This is the PERFECT test for DTC32 EGR, WHICH IS DUE ONLY TO EVAP VACUUM CIRCUIT LEAK, typically indicated by SES light, intermittent at highway speed, which is when the EVAP gets purged.

'02 Frontier...

edit:
Found this goody:
Which one do I jump, to apply vacuum to entire EVAP circuit?

Mods; change the thread title please to 'po0455 / vacuum leak diagnostics (with pics)'.

I've ID'd the EVAP cannister purge solenoid, and started to trace the vacuum leak.

The PROPER way to activate the vacuum TO the EVAP vacuum circuit is to pull the EVAP solenoid connector, and apply 12V to the solenoid, and ground it accordingly.

Since I'm not familiar with the polarity of the solenoid (note the wires are not red (+) or black (-), what I did first was just by-pass the solenoid. The red arrow is from the solenoid INTO the intake, and the yellow is FROM the EVAP cannister (still haven't taken the search dive yet) TO the solenoid.

So I pulled the trigger with the by-pass plugged in, BUT, it did NOT start idling rough/loping idle, as I expected a vehicle with a vacuum leak to do. EVERY internal combustion engine with a vacuum leak - a 30 year old lawnmower or a new car on the lot 0 miles will lope idle with a vacuum leak.

Then I remembered in the diagnostic schematic, earlier post, said 2 solenoids had to be jumped, but I'm not familiar yet with that OTHER valve. So at best so far, the leak is NOT between the EVAP solenoid and the next valve going to the EVAP cannister.

 

[tonylong]

If you arre still using the original Multec injectore be aware they are not ethanol fuel compliant. Ethanol will rot the seals and cause leaks. Replace the injectors with Bosch Design III injectors. I got mine from Jon at FIC. My running problems went away.