Fuel line issues??

[Pescador95]

Hi all

Recently, when driving my T4R when 'cold' (immediately following start up and before the engine reaches its proper running temp), I've noticed a slight lag in the response time when shifting into 2nd, 3rd, and 4th gear. As I release the clutch and press the accelerator, the engine nearly shuts down before (presumably) the gas reaches the cylinders. Once the engine warms up, it runs great, even after idling at a stop light. On a side note, I've noticed my gas mileage has significantly decreased of late (4-6 mpg less than normal).

I checked the air filter---its fine. Is this a fuel pump issue? Or has the vacuum in the fuel line been compromised? The peculiar thing is that it stops once the engine warms up.

It should be noted that I don't live in a particularly cold climate (currently in east TN, temps may slightly dip into the 20's overnight).

I drive a '95 SR5 4x4 3.4L V6

Any advice would be much appreciated, thanks!

 

[Quatre Coureur]

Fuel filter? Are u sure its a 3.4 n not a 3.0? I thought 3.4s came out in 96...

 

[fourwd1]

Places to start looking are Cold Start Injector circuit and EFI coolant temp sensor.

 

[Greg_Canada]

Sounds competely normal, 20 deg f is pretty cold. Your mileage is bad because you are likely taking short trips and your engine is warming up (burns alot of fuel until its warm). You engine lags because everything is cold and tight, and the oil is thick. Once it warms up the clearances go back to normal and oil thins out. A block heater would help these issues significantly.... Btw both my 3vze and 5vzfe do this (3vz is more prone to it tho)

 

[KidVermicious]

I don't know that 20 is that cold - we can get to 10 deg f or lower here, and I don't have issues like the OP describes. I agree that the mileage is likely due to winter temps, but not the stumble he's got.

I agree with fourwd1, if it goes away when the engine hits operating temp it's probably the cold start injector.

 

[Pescador95]

Thanks for the quick responses. Greg_Canada: in re: mpg, I should have noted that I got the 4-6 mile bump while driving across the country, which is why I was so surprised. I may not have done a suffucient job describing my problem, but I'm almost certain that it is not cold enough here to cause anything like this...

No idiot light has come on in the dash about the problem yet, which makes me think the sensors havent quite failed completely. I'll get a diagnostic run on her post the results

 

[Pescador95]

UPDATE: A new problem surfaced before I was able to take my 4R into the shop: I started experiencing throttle surges while idling (b/w 1000 and 1500 rpm, so nothing major), so I figured something like the throttle body needed a good cleaning. Turned out, I was right. After a good cleaning, the throttle surges stopped. Also, the mechanic told me that my idle had been altered in the past (there's an ideal air/fuel setting it needs to be set to), so he restored it to default, and it runs like new.

Quick novice question: I was under the impression that cars with EFI did not have a throttle body? Does the fuel enter through the throttle body before splitting towards the EFI ports on each cylinder? I figured it was one or the other...

Thanks again for all the responses. I hope this can help somebody in the future