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Car Forum / Ford / Ford Trucks / October 2006Rebuild 87 ford 302 EFI now runs very rich
I just rebuild my ford pickup motor that is a 1987 ford 302 EFI Mostly stock But a comp cam and headers now it is very rich I can't seem to find any probloms tested vacuum lines and I have tested a few of the sensors. but I was more wondering if, with a larger cam I could be loosing my vacuum that runs things like the map and such >I just rebuild my ford pickup motor that is a 1987 ford 302 EFI Mostly >stock But a comp cam and headers now it is very rich I can't seem to >find any probloms tested vacuum lines and I have tested a few of the >sensors. but I was more wondering if, with a larger cam I could be >loosing my vacuum that runs things like the map and such Don't know whch cam or cam specs you installed but, Comp does (or did) make a cam that should be compatible with your EFI system. If the cam you installed has more aggressive specs, it is not only possible but probable that the MAP sensor will not be able to deal with it. A MAF system can deal with considerable engine modification. You may end up going to FordRacing for a MAF conversion kit which includes a new ECM, an MAF sensor and an overlay wiring harness - don't know if these are still available for that vintage. You may be on your own to either use a milder cam or figure out which parts to do the conversion. I hope you were not looking fo a noisy/lumpy idle as awas the caser with carbed engines with long duration performance cams. A properly tuned MAF system will not only deal with it but all but eliminate the unsteady idle from any streetable cam. The unsteady idel was caused by a low vacuum sugnal. The MAF only meters the air actually entering the engine. Good luck Lugnut When I bought the rebuild kit the salesman said that it was compatable with the efi it is part number 31-216-2 .447 lift Intake and Exhaust Intake 24 BTDC 56 ABDC Exh 64 BBDC 16 ATDC >When I bought the rebuild kit the salesman said that it was compatable >with the efi it is part number 31-216-2 .447 lift Intake and Exhaust >Intake 24 BTDC 56 ABDC Exh 64 BBDC 16 ATDC I have used the Comp 260 deg and the Crane 262 and 268 deg cams with speed density with decent idle charachteristics with the exception of a slight rpm roll at idle. If you are running too righ with that duration, you should be looking at things like the ECT and ACT sensors and checking their values against a resistance chart that can usually be found in a good shop manual. Most all of those Ford EEC-IV systems used sensors with similar values. The MAP sensor works on a signal frequqncy and needs a frequency meter to check it against the charts. It is not usually the problem. One of the most frequent failure causing a rich mixture in them is a bad or failed fuel pressure regulator. That engine should have about 32-35 psi at idle depending on manifold vacuum. Another frequent problem with vacuum and therefore, fuel pressure is ignition timing. Make sure you have pulled the SPOUT connector to set the vacuum or you will have lower vacuum, higher fuel pressure and richer mix. Also, make sure your TPS is reading .5>.9 volts. 1.0 VDC or more and the ECM starts the fuel and timing curve. Before you chack this, you will need to make sure the base idle is pretty close. If you have never touched it, it should be OK. Your cam should be fine if you have it correctly timed. You should not have to do any conversions or modifications for the engine to run properly with that grind. I hope you also took the time to set the lifter preloads correctly. Ford Racing has a shim kit to make sure they are correct. Lugnut >>When I bought the rebuild kit the salesman said that it was compatable >>with the efi it is part number 31-216-2 .447 lift Intake and Exhaust [quoted text clipped - 28 lines] > > Lugnut the problem you outlined is one that is common when upgrading the 87 style speed density fuel injected systems. the parameters built into the computer just can't handle the increase. there are some aftermarket fixes that try and cheat this system, but in the long run you will be better off converting your car to the Mass Air fuel injection system. many companions sell this as a kit, or there are dozens of internet sites that will walk you through it with junk yard parts. >>>When I bought the rebuild kit the salesman said that it was compatable >>>with the efi it is part number 31-216-2 .447 lift Intake and Exhaust [quoted text clipped - 36 lines] >a kit, or there are dozens of internet sites that will walk you through it >with junk yard parts. I have done several of these type setups in that vintage. Basically, the ticket is a donor Mustang GT of early '90's vintage for a complete mass air system. He may need to get hands on a wiring diagram for the ECM and wire harness used and change the injector sequencing to match the firing order of his cam if he used a stock firing order cam. If he got lucky and got the cam with the HO firing order which I have used a couple of times, he won't have to change the GT ECM injector firing order. Once he gets the engine straightened out, a 4.10:1 rear gear will really wake it up. Lugnut I put a vacuum pump on the map and pumped it up to 15 inch of vac and the truck ideled but the problom is that in the manifold I had about three and a half everyone that I talk to says that the specs on the cam should not cause this. I was thinking that maybe wrong cam was sent in the box I am in the middle of doing a compretion check on the cylinders so far I am coming up with about 100 PSI I am going to finnish it tomarrow and if I don't find any cylinders that stand out I am going to pull a valve cover off and double check the lift and duration of the cam just to make sure any other ideas would be helpfull. I was also wondering about the timing chain. I checked it about six times but if I could have screwed it up. >I put a vacuum pump on the map and pumped it up to 15 inch of vac and >the truck ideled but the problom is that in the manifold I had about [quoted text clipped - 7 lines] >wondering about the timing chain. I checked it about six times but if I >could have screwed it up. With vacuum and compression that low, I would suspect you have the cam off on timing. I would usually expect around 14-15" or better vacuum with this setup - certainly not 3-4". Even one tooth will do this. If you used a multi slot crank gear, make sure you have it set right. For this setup, I usually like to use either the straight up slot or a 4 deg advance. A bit of advance gives better response off the bottom end. It usually results in more vacuum and compression. Keep in mind that many cams have a 5 deg advance ground in. Comp and Crane both usually do this. Be sure you check the cam spec card that came with it. If it is ground with 5 deg advance, do not use an advanced gear slot. Install it in the straight up position on the crank sprocket. You should have the timing marks lined straight up with them pointing at each other. Use a straight edge thru the centers to be sure. If you have and can use a degree wheel, that will confirm proper timing. If I am building a performance engine on the stand, I will check the timing and lift on every lobe of the cam. I have seen one or two that were not correct but, this will usually show up on the compression test if one or two are out of spec. Also, make sure of which ignition firing order the cam is. Many performance cams use the HO firing order which is the same as the 351/5.8L engine. I hate to say this but, many people cannot identify a misfire or crossfire in an engine with a performance cam. This will kill it. Again, with the exception of a slight rpm roll at idle, this cam should be pretty darn smooth. One last thought: make sure the part folks did not give you a cam for a roller motor. Your vintage engine needs a cam for flat tappets. I have seen this happen. I may not be noticed by a novice with this engine until you try to run it. If you bought a cam kit with lifters in the same box, it should be OK. If they came in separate boxs, get the numbers and call CompCams tech for verification of compatibility. Lugnut I pulled the front cover off, and I had forgot to put the dal pin in the cam to cam gear Thank you for all of your help >I pulled the front cover off, and I had forgot to put the dal pin in >the cam to cam gear Thank you for all of your help UR welcome. It was late cam timing that bit U. I'll bet you remember it next time! Lugnut |
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