ho conversion with problems

Topic: ho conversion with problems (Read 2017 times) previous topic - next topic

ho conversion with problems

June 04, 2005, 04:36:03 PM

i installed a 88 ho into my sons 88tbird everything seems fine but i have a slight hesitation after car gets past hesitaion it runs great . i used complete engine from 88 gt mustang i also used computer from the gt the only parts that are still tbirds are map sensors and dist module. i have the timing advanced as much as possible with out sparkknocking . tps voltage is at .98 volts . im not sure what elese to do

Re: ho conversion with problems

Reply #1 – June 04, 2005, 07:08:39 PM

Same problem here, but I haven't done the conversion yet...

Re: ho conversion with problems

Reply #2 – June 04, 2005, 07:20:48 PM

Does this hesitation occur every time you accelerate from a stop? Is it only when you accelerate for the first time after starting the car?

Re: ho conversion with problems

Reply #3 – June 04, 2005, 08:13:39 PM

everytime i go to accel hard ,slow take offs are no problem its just on harder accels that its a problem.

Re: ho conversion with problems

Reply #4 – June 04, 2005, 09:38:13 PM

whats timing set at ??
your using HO firing order right ??(i know dumb question just thowing it out there) double check the firing order anyway..
how did the car run before the swap?? just curious..

Re: ho conversion with problems

Reply #5 – June 04, 2005, 10:14:04 PM

yes firing order is correct for ho ,timing is set between 11&12 this is about as high as i can get it with out dealing with spark knock ,
car was running ok before swap motor was just old and weak 198000 miles .since this is my sons car and hes in collage i wanted to give him a new motor so his car would be dependable and have some more horses . the car runs great except for this hesitation ,it has plenty of power .i was hoping someone had ran into this problem before ? i hate to spend money on parts that im not positive i need ,but i may try a new map sensor i think these are more sencitive on speed density cars?

Re: ho conversion with problems

Reply #6 – June 04, 2005, 11:11:43 PM

i wouldn't throw a map sensor on it.. Sounds like a waste of money.. How about you check the EEC for any codes that might help engine off and engine runnig tests. Also run a cylinder balance check with the code reader maybe you will get lucky (or not lucky if it is a bad problem) and find a weak cylinder that is causing the problem....

Re: ho conversion with problems

Reply #7 – June 04, 2005, 11:31:41 PM

ran codes koeo everthing pass ,engine running code 12 which acording to my code says iac not working ,but iac seems to be perfect if i unplug it engine drops about 150-200rpm also this is a fresh motor i just put together .came out of a 88gt i had ,so i am positive we have no mech problems . it just this slight lag beteewn push the gas pedal and motor responding 10th of second (est) if you drive normal you dont really notice problem its mainly when you put your foot in it .its really got me stumped its almost like theres not enough fuel then it cacthes up .its a delayed reaction you step on the gas car thinks for about a 10th of a second and your gone like a bat out of _ell.

Re: ho conversion with problems

Reply #8 – June 05, 2005, 09:29:35 AM

Did it pass the cylinder balance test?

you said you checked the tps right? and its set at .980... put a meter on it again and monitor the voltage while you open the throtle blades (very slowly) make sure the tps has no dead spots where it doesn't show a voltage for a certain blade angle..

Re: ho conversion with problems

Reply #9 – June 05, 2005, 12:40:26 PM

balance check ok i will check tps again i only check it for volts at idle and wide open before

Re: ho conversion with problems

Reply #10 – June 05, 2005, 01:39:58 PM

My 88 Bird does this to, but I dont have an HO. Mine usually quits after while but nontheless its still annoying.

Re: ho conversion with problems

Reply #11 – June 05, 2005, 08:05:20 PM

tps voltage checks good all the way thru .no dead spots ,but i did notice that i have car idleing higher than specs if i lower idle to 600rpms it start rpms start going up and down like its hunting for the right spot but if i keep it set at 700-750 all is fine ,all the mustangs i had were 5speeds and they all idled around 750 no problems but the autos call for 500??

Re: ho conversion with problems

Reply #12 – June 06, 2005, 09:04:49 AM

500 is too low. That 750 you got her at is fine. Most of the stuff I've seen on the issue says 675 is the target RPM

Re: ho conversion with problems

Reply #13 – June 06, 2005, 01:47:23 PM

I did my H.O. conversion and ran into the same problem. It was being starved of fuel. They are even known for doing that in the factory cars. I installed a 190ltr Walbro pump and it went away. Maybe that will do it for your car also.

Re: ho conversion with problems

Reply #14 – June 07, 2005, 04:51:35 PM

i will try and check fuel volume and pressure this weekend when my son has the car back home ,he says its been running good so far this week and doesnt even notice the problem untill he really kicks it