weird shuddering/rough startup/bad gas mileage

[BlackDynamite]

Well recently, my car has started running rich and had a rough startup(and getting bad gas mileage). Well it's been running pretty good, still have the waterfall effect, and the rough idle goes away when the fan kicks in. Well i went on a 20 mile run and back to a nearby city. Ran GREAT getting there and on the way back, i start to notice a skip. I was like ok maybe some bad gas or something. Then it started skipping really BAD when i started to give it gas. So i start driving and my car starts to shake violently only when i gave it gas. So i check gages. Oil pressure and temp fine and voltage as well. I thouhght it jumped timing so, i pulled over. The engine purred like a kitten. revved it, turned off engine, made sure no leaks and made sure spark plugs were good. Everything good. Left and it was shuttering as before. I was almost to the house to drop it off when about a mile away it cleared up and ran fine. Drove it around the town like nothing had ever happened. So i check all fluids, clean, no metal, no murky, all looked normal. WTF happened?

Checked, no codes and no check engine light on.

 

[BlackDynamite]

I thought maybe something got in the gas and cloged the injectors....could it be fuel pressure regulator making it run rich? Maybe a blown head gasket?

 

[supramacist]

What do you mean by "skip"?

Do you mean like it was missing?

 

[BlackDynamite]

yeah like a complete cylinder just stopped firing. at a point it almost felt like 2 or 3 stopped....

 

[AJ'S 88NA]

yeah like a complete cylinder just stopped firing. at a point it almost felt like 2 or 3 stopped....

Have you checked the injector clips?

 

[BlackDynamite]

yep all injectors fine. I looked in my over flow tank, which has been losing water, and noticed there was a little bit of a oily look to it. Kinda like when you have salad dressing and the oil and vinegar separate. So i'm thinking i should go and re-torque the head bolts. I have a metal head gasket that i torqued down to 77 ft/lbs with arp.

 

[AJ'S 88NA]

yep all injectors fine. I looked in my over flow tank, which has been losing water, and noticed there was a little bit of a oily look to it. Kinda like when you have salad dressing and the oil and vinegar separate. So i'm thinking i should go and re-torque the head bolts. I have a metal head gasket that i torqued down to 77 ft/lbs with arp.

Not a good sign.

 

[supramacist]

I torqued mine to 85lbs. Hasn't leaked anything since.

Unless you cleaned out your overflow it could just be oil residue.

There almost has to be something more wrong that you haven't found yet.

I'm wondering about your fuel filter. I have never had to deal with such a problem.

Sorry I'm not more help BD.

 

[BlackDynamite]

AJ: well, thats what i'm thinking. Though when i took off the radiator cap, there was brown all over the rubber, and some inside the radiator. ON a new radiator and cleaned motor after rebuild. Wtf. Using 50/50....new thermostat, had to change it once because of brown crap and flushed engine while running. Still got it....But when it warms up it runs like a champ.

SM: Yeah i'm thinking of changing the fuel pump and filter. But i gotta drop gas tank to do all of that shit and might as well change all of it while it's down. I just think there is a head bolt loose or something....making it not seet correctly .

 

[AJ'S 88NA]

Don't put it off, coolant can do wonders for bearings

 

[supramacist]

YA if you really think so retorque them.

 

[BlackDynamite]

now it's weird....if i don't have my heater set to 85, the car runs worse until i switch it to 85(which makes the waterfall sound...then it runs great)....i think i have a bhg.....

 

[InFrnt0fU]

now it's weird....if i don't have my heater set to 85, the car runs worse until i switch it to 85(which makes the waterfall sound...then it runs great)....i think i have a bhg.....

If you did the rebuild with ARPs head bolts/studs, then they should have been torqued to 85ftlb per ARP specs. I'd say drain everything and pull the head, but I'm the careful/anal type...and if you just did a rebuild and poured money into the car, might want to pour some time into checking the MGH condition.

 

[BlackDynamite]

shit i did 77, and it didn't say 85 when i got em....well, time for a retorque...

This is how i got em from HPF...i was disapointed because the other supra i was rebuilding/converting to manual, we ordered the same thing and the came in a box, and had instructions and stuff....

 

[InFrnt0fU]

Yeh mine came in the ARP box with instructions. Says 85 ft lbs
Have you been boosting?

 

[BlackDynamite]

na, auto

 

[InFrnt0fU]

Still not good but there would be a greater chance for HG problems if you were boosting. I'd say get the oil system and coolant system completely flushed, retorque and see how she runs.

 

[BlackDynamite]

Thats exactly what i'm doing sunday:]

 

[stakie]

How did you make out with your problems?

I'm having a similar problem. I'm having a shuddering when I'm driving, rough shaking (not violent yet) on idle. At first, I thought it was a spark plug wire that was loose. I checked, and #5 was indeed loose, but I plugged it back down; still the same issues.

I decided to change the sparks. They were the same model number as the TSRM for an NA except, they had the "S" at the end, instead of the "P" as recommended (Standard vs Platinium I presume). One thing I noticed when I took off the spark plugs closer to the firewall. They were soaked with oil. #'s 1 & 2 were not. Is that normal? I'm going to assume it's not. I couldn't get to 3 &4, really hard to take off. The way the TSRM says to get it off is just ridiculous, and I was also looking for w writeup on changing, but I didn't find one for the NA car.

But anyway, the shudder/idle/the way the car drove was a little better, but not great. Just better than before.

Another thing I noticed: when I took the oil cap off whilst the car was idling, it almost cut off, like the idle would go down to like 300rpm. But as soon as I put it back on, it would go back up to like 7-800rpm. So, that's my symptoms. Is that similar to what you have, or could this be a vacuum leak? No visible signs of a bad or broken hose for leaking...

 

[BlackDynamite]

Ok, well i went and re-torqued the head bolts to 85ft/lbs, one was loose. Others were fine. I changed all the spark plugs, just to do it while i had it apart and all the plugs were fowled. Dirty, cracked, oily as a MotherFudger. Number 3 and 5 looked the most normal. Number 2 was the worst. There was a little bit of antifreeze ,a drop or two on number 2. But oil was leaking from the valve covers righter there and antifreeze from a loose hose on the throttlebody, so over time, it just leaked in. Now it starts up fine, every once in a while it will waterfall effect only when it is super cold and only for a split second.