problem on a GE, fuel related.

[87hilux7mge]

so, my freind has an 88 n/a. running on MS2, gte coil pack, ford throttle body, header, running on map. car was working great this last summer, the motor is completely rebuilt, and had no problems until recently.

he started it up, was having fuel pump problems. so he switched it for a stock fuel pump. no change, will not idle for crap, runs pig rich at low rpms, runs lean at higher rpms. also, his map sensor is logging fluctuations through out the rpm range. i thought a faulty fpr, so we swapped in a new one, no change. checked plugs, they were all black. cleaned them, no change. checked mechanical timing, no problem. electronic timing, no problems. hes pulled necessary fuel, no change. changed pulse width to the max, no change.

getting great spark quality. then we noticed something, wierd... tubes 1, 2, and 3, are normal temp when operating, no touchy. 4 and 5, cool to touch, barely warm, i can grab them at full throttle and no heat increase. 6 is warm, but not enough that i have to remove my hand. it sounds like hell when it runs, like a subaru. lopey.

hes thinking stuck valves, but im still thinking a faulty map or fpr. pushing tons of fuel at low rpms, but not ramping up as it should with rpms.

anyone have any ideas??

[cre]

MAP sensor, FPR or (if he's running one) fuel pump resistor. MAP sensor is the first thing I'd check and then I'd reset and reupload the tune he's using from a backup to make sure nothing's just screwy in the MS' memory. All you need to test the MAP sensor is a multimeter and a reasonably accurate vacuum pump.

If the tubes you're referring to are the exhaust manifold runners, well, the temp drop could be accounted for by the excess fuel preventing a full burn (if it's not completely blowing out the spark as it is). Sticking valves aren't terribly common on these engines.... but they're not too hard to check for so feel free, I doubt that's the issue though.

[87hilux7mge]

well i got some news for this one. he did a compression check, 160 all the way across, except #6...zero compression. checked the cams and valves, one of the #6 exhaust valves was stuck open and spit a shim out, lodged it in the bore and stuck it open permanently.

before that, he had cleaned his plugs and no improvement.

i had the same suspicions about the fpr or map. since weve checked everything else, excluding the map. i also suggested he reload his tune, but he was hesitant to do so. im still firm in that thought.

basically he needs a new exhaust cam and to fix the head, hes pretty sure the bore is fixable so now hes part hunting.

anyway, ill update as needed, but im pretty sure the faulty map is a good possibility as well as the tune screwing up itself..

[CanadianBak'inSupra]

really off topic but..

is he running one of the 75mm TB's??
check out this madd twin 57mmTB from a mustang cobra i cant remember where i found this pic and write up:
http://users.tpg.com.au/users/loats/index.html
tons of good info in there.

[87hilux7mge]

ive seen the twin 57mm install. its kewl, but kinda pointless in my mind. twin 57's are too big for a 383 small block, let alone a 181 inline six. throttle response may improve, but low end torque is bye-bye.

anyway i am unsure of his TB size, but its not massive. he ran this car N/A last year a few times at the drag strip on giggle gas. supposedly pretty decent for an N/A, he has yet to dyno it cuz it sat and started running like crap. so once he finds some stuff to get it back up to par, hell prolly take it and his fatty turbo'd mk2 back to the dyno and do both of them.

anyway, hes working on it. i told him to reload his tune and double check his internal MS map to make sure its working right. other than that, everything appears to be in order.