Idle issue after IM gaskets

kimcrwbr1 · Apr 23, 2014

Did you reset the computer. Disconnect the battery for 1/2 an hour? On older vehicles you need to reset the computer whenever you change or clean a sensor. That way the computer can reset the new values after a couple complete warm up cycles. Just a thought before you take it back apart, was the battery disconnected when you were doing the work?

PsYcHo_FrEkE · Apr 23, 2014

RonD said:
Spec is 40-50psi
Also if possible check fuel pressure gauge on another engine or even a tire that has a known pressure, gauges can read a few pounds off so best to have a baseline test of a known pressure.

Fuel pressure regulator(FPR) is opened and closed by vacuum pressure in the intake.
Vacuum is highest at idle so fuel pressure would be lowest at idle.
Pull off the vacuum line on FPR and check it for fuel smell, if fuel is present replace FPR.

42psi is a bit low with FPR's vacuum line disconnected, this would either be from an older fuel pump or a small leak.
What was fuel pressure with engine off, it should drop a few pounds then stabilize, and stay without dropping any more, if it continues dropping then there is a leak, if there is no gas smell anywhere then could be FPR valve or an in tank leak, i.e. fuel pump check valve(back flow preventer)

But the 32-42psi should be fine for engine operation, the computer would open injectors longer when O2 sensors report leaner burn from lower pressure.

Been gone all day. Haven't checked the fuel pressure with the engine off. I was just shooting in the dark to see if it could potentially be even part of my problem.

kimcrwbr1 said:
Did you reset the computer. Disconnect the battery for 1/2 an hour? On older vehicles you need to reset the computer whenever you change or clean a sensor. That way the computer can reset the new values after a couple complete warm up cycles. Just a thought before you take it back apart, was the battery disconnected when you were doing the work?

I've disconnected the battery every time I've taken it apart or plugged anything back in that I missed. Been pretty meticulous about that detail since I'm trying so hard to pin down the problem.

Tbarnes93 · Apr 24, 2014

Could be maf or ect

Sent from my HTCONE using Tapatalk

PsYcHo_FrEkE · Apr 25, 2014

Tbarnes93 said:
Could be maf or ect

Sent from my HTCONE using Tapatalk

I've checked the MAF voltages already. MAF seems to be working fine.
How would the ECT sensor would cause erratic idle similar to that of a bad IACV?
Truck seems to run fine when accelerating, but falls on its face when I let off. If I stop the truck too quickly or put too much strain on the steering while moving slow (like through a parking lot) the engine stalls out. That being said, when sitting at idle without a load on it the problem is prevalent even in higher RPM ranges.

I'm thinking vacuum leak, but I keep striking out trying to find it. I can't seem to find it with ether.

PsYcHo_FrEkE · Apr 25, 2014

The problem isn't doing anything but getting worse. I'm to a point now that I'm considering replacing all of the vacuum lines. The problem is that I don't know what to do about the hard lines.

Is there a kit out there somewhere for these?

Are they a dealership part?

They seem rather thin... would trying to rebuild the system throw off the vacuum from the increased inside diameter if I replaced them with all rubber hose?

PsYcHo_FrEkE · Apr 25, 2014

I got ahold of a vacuum tester. The hard lines are good. The only thing I could find was a slow leak in the evap to TB line. I'm not sure how much vacuum the line should hold, but I pumped it up to about 15-20 psi. The guage pulled down to 12-13psi slowly and nearly stopped pulling around 10psi. Would this be enough of a leak to cause this much havok?!

RonD · Apr 25, 2014

If you have a vacuum gauge then go here:
http://www.gregsengine.com/using-a-vacuum-gauge.html

See if you do have a vacuum leak first.
Best if engine is warmed up first

PsYcHo_FrEkE · Apr 25, 2014

Replaced evap canister hoses. They may have been a problem, but definitely not THE problem...

While I'm thinking about it, are the solenoids/sensors in line with the hose that goes between the TB and the evap canister?

PsYcHo_FrEkE · Apr 26, 2014

I'm really thinking about those pintle caps again. I mentioned them in my first post, but nobody commented. Here is (basically) what the originals looked like:

What the aftermarket ones O'Reilly's sold me looked like:

PsYcHo_FrEkE · Apr 27, 2014

I'm not getting anymore feedback from you guys, but I'm going to keep up the thread in case anyone else has this problem.

For anyone following this, according to the seller this repair kit fits my truck:

Ford Mercury 4.0L V6 Fuel Injector Service Repair Kit O-Rings Filters Seals

The kit is said to fit all models 97-98 Ford Explorer. With any luck maybe this will fix the problem. My thoughts are that the pintle cap I used is creating a dead space between the holes for the spray and the pintle cap (something I was concerned with even when I bought them, but at the time couldn't find anything better and needed the truck back together). My theory is that the dead space is building up with fuel and "choking" the engine. Instead of getting a spray, I'm likely getting a stream. My theory goes on that the reason I don't have any issues at 30+ mph while accelerating is because I'm pushing more gas into the system which is forcing all of the fuel through the small hole in the pintle cap and is allowing the fuel to properly disperse into the cylinder. We'll see what happens when the parts come in. I'll keep you guys updated in case anyone is still following this...

PsYcHo_FrEkE · May 8, 2014

I've changed the pintle caps and filters. The idle problem is gone now. I guess that was the problem. Now I'm just waiting to be sure that CEL doesn't come back.

Idle issue after IM gaskets

Well-Known Member

New Member

New Member

New Member

New Member

New Member

Official TRS AI

New Member

New Member

New Member

New Member

Sponsored Ad

Sponsored Ad

Today's birthdays

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals