autocomman
New Member
- Joined
- Jun 22, 2010
- Messages
- 6
Well first lemme get outa the way Im a new member, though Im not new to turbo cars...im a big volvo nut and have messed with turbo cars for a while, im also a diagnostic auto tech, have been for 10 years and this is where my question comes in.
We have a customer that brought in his 86 grand national. Long story short, he popped the motor, it was rebuilt and put back in, all stock. The car on the other hand has been butchered, molested, massaged, and all in all its had a rough life. It had 2 questionable fuel pumps, one in the tank one external. A turbonetics delta II waste gate, missing the boost control solonoid, and tee with the oriface is missing also, the wiring is thrashed. I'll make this story as quick as i can, heh
Ive put a stock pump in the tank, new filter, drained the fuel and put fresh premium and replaced the FPR, ive got a solid 37 psi with no vacuum on the regulator, if it boosts, it rises properly. I dont know what injectors are in it but they are not stock. The ECT and knock sensors are new A/C delco parts. The wiring, not by me was taped up so there shouldnt be any bare wires in the EFI harness. Battery and cables are new, all the grounds are there and are clean and tight. The waste gate is hooked up with a 7 lb spring in it, so boost is on the limited side right now, im fine with that till i get the rest of the car straightened out. Oh and there is no cat, so you can rule out plugged exhaust, heh.
The car is lean. Verified with the o2 sensor, scanner, its setting a lean code also. It runs as though its lean too. Some hesitation when getting into boost, its just not right. The idle is rough sometimes and it will surge, sometimes with a stall. Ive set the IAC properly so its a 20-25 steps with the TPS at .41 volts, and a sweep to about 4.7 at WOT. Intake hoses and boots are new, and the MAF was not. So we ordered one and i put it in. It was a standard brand part, not my choice, just what we could get at the time, and it looked different. It had like a narrow section in the middle of the tube, whereas the original one was a straight tube. The connector on the new one was also perpendicular to the body, and the old was was parallel. At idle with the old one it was 4-5 GMPS, the new one seemed to idle better and have better throttle response. It also idles closer to 6-7 GPMS. At 2000 RPM it also had a higher GPMS count. But punch the throttle at all and as soon as you get past that 0in vacuum and just touch boost it falls on its face, hard. you can do this in park just by revving it, not that hard even. Its not loosing spark, its frekin lean.
Now my question is am i looking at a faulty MAF? signs say yes but 2 'new' MAF sensors would say no, then again its defiantly possible they are not calibrated right anyway. It seems like they hit a point and just wont register more air flow. According to numerous parts sites, I have the correct standard replacement, but im not convinced. This guy has spent way too much money on this car, and he wont give up. Ive been working on finishing this car for the last 3 weeks and we need to make it right and get it out of the shop. Its preferred to keep stock parts in it, with out the MAF translators and all, but if thats what I got to do, then we will prolly do it. But I need to be absolutely convinced that will fix it ya know? We are so deep in this car its retatded.
SO, anyone got any ideas? Sorry for the long thread, and feel free to be as technical as you like, like I said, not new to turbo cars. My toy is a stroker volvo thats got a T3/T4 turbo, a nissan UD intercooler, 3" exhaust, ford T5, etc etc and megasquirt and spark to top it off.
Mark
We have a customer that brought in his 86 grand national. Long story short, he popped the motor, it was rebuilt and put back in, all stock. The car on the other hand has been butchered, molested, massaged, and all in all its had a rough life. It had 2 questionable fuel pumps, one in the tank one external. A turbonetics delta II waste gate, missing the boost control solonoid, and tee with the oriface is missing also, the wiring is thrashed. I'll make this story as quick as i can, heh
Ive put a stock pump in the tank, new filter, drained the fuel and put fresh premium and replaced the FPR, ive got a solid 37 psi with no vacuum on the regulator, if it boosts, it rises properly. I dont know what injectors are in it but they are not stock. The ECT and knock sensors are new A/C delco parts. The wiring, not by me was taped up so there shouldnt be any bare wires in the EFI harness. Battery and cables are new, all the grounds are there and are clean and tight. The waste gate is hooked up with a 7 lb spring in it, so boost is on the limited side right now, im fine with that till i get the rest of the car straightened out. Oh and there is no cat, so you can rule out plugged exhaust, heh.
The car is lean. Verified with the o2 sensor, scanner, its setting a lean code also. It runs as though its lean too. Some hesitation when getting into boost, its just not right. The idle is rough sometimes and it will surge, sometimes with a stall. Ive set the IAC properly so its a 20-25 steps with the TPS at .41 volts, and a sweep to about 4.7 at WOT. Intake hoses and boots are new, and the MAF was not. So we ordered one and i put it in. It was a standard brand part, not my choice, just what we could get at the time, and it looked different. It had like a narrow section in the middle of the tube, whereas the original one was a straight tube. The connector on the new one was also perpendicular to the body, and the old was was parallel. At idle with the old one it was 4-5 GMPS, the new one seemed to idle better and have better throttle response. It also idles closer to 6-7 GPMS. At 2000 RPM it also had a higher GPMS count. But punch the throttle at all and as soon as you get past that 0in vacuum and just touch boost it falls on its face, hard. you can do this in park just by revving it, not that hard even. Its not loosing spark, its frekin lean.
Now my question is am i looking at a faulty MAF? signs say yes but 2 'new' MAF sensors would say no, then again its defiantly possible they are not calibrated right anyway. It seems like they hit a point and just wont register more air flow. According to numerous parts sites, I have the correct standard replacement, but im not convinced. This guy has spent way too much money on this car, and he wont give up. Ive been working on finishing this car for the last 3 weeks and we need to make it right and get it out of the shop. Its preferred to keep stock parts in it, with out the MAF translators and all, but if thats what I got to do, then we will prolly do it. But I need to be absolutely convinced that will fix it ya know? We are so deep in this car its retatded.
SO, anyone got any ideas? Sorry for the long thread, and feel free to be as technical as you like, like I said, not new to turbo cars. My toy is a stroker volvo thats got a T3/T4 turbo, a nissan UD intercooler, 3" exhaust, ford T5, etc etc and megasquirt and spark to top it off.
Mark
